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PROGRESS OF SCIENCE.
TRANSPLANTATION OF TISSUES.
INSECTS' HEADS CHANGED.
I have now been /üble to consult the German text, ia the "Anzeiger" bf the Vienna Academy oí Sciences/ describing experiments in which successful changes of heads are stated to have been made between different living insects (writes the Scientific Correspondent- in me London "Times" of November 28); The insects selected were/adults and grubs of water-beetles, common butterflies, meal-worms, and water boat-men. The heads of two insects were taken off with sharp scissors and at once exchanged. No suture was required, the little drop of exuding fluid acting as a cement. In a /few weeks recovery was complete, the power oí co-ordinated locomotion and of feeling was restored, and sexual con- gress took place.
The insects were controlled by their new heads, notiiy their old bodies. Cer taiù forms of colour'and. pattern seem to he directed through the eye and brain. When the heads bf the caterpillars of Vanessa io and Vanessa urticae were exchanged, the butterfly followed the habit of the species the bead of which had been bestowed on it A Dytiscus beetle provided with the head of a Hy- drophilus lost the yellow 6tripe and glossy brown .surface of its species and assumed the -dull black colouration of Hydrophilus. A female Hydrophilus water beetle, provided with the head of a male of its own species, courted nor- mal (females actively; a' male given, a female. head retained the normal pas- sive habit of females in the presence of the other sex. -
These startling results are stated to have been obtained by Mr. Walter Fink - 1er, and. although they do not seem
to have been, vouched for by. Dr. Hans Przibram, a biologist bf the highest re- pute, they cóine frota his laboratory, and follow <a line of investigation on which he has long been engaged, Never- theless, ,1 am not convinced, and- -think a loss Of head on the part .of the ex- perimenters more likely, than au ex-
change of the insects' heads. .
T taite no a priori objection to what is stated to have, followed the change of heads. - I aaj . ready to. believe that the important part of the nervous sys- tem in the head controls. sexual display and colouration. I am also ready to be- lieve that a full-fed grab might survive the shock of decapitation, live for some . time, and even go through its meta -, morphosis. But the grafting' of an- other head is a different affair.
? The head, of an insect contains, the brain/ the eyes, other organs of ; sense, and the mouth and jaws. It is joined to the-body by a slender and flexible neck," through which pass the gullet, the large.nerve cords; uniting, the brain
-with ' jthe important parts br thé uer- . vous ^system wliich - lie in the body, .branches of the, trachae or ringed con- duits which carry "ak to aerate the brain, and the blood channels which feed
it. - - ?
Assuming tliat the head and the body both-remained alive and-in the requisite approximation Nfor a sufficient length of time, it is conceivable that the new brain might acquire continuity witti the i nervous system of the alien body. The President bf the British Association re- cently described how, in. ibe healing of the nerves, of vertebrates, fibres grow out from the ' nerve cells; and with au uncanny power bf direction, grope and thread their way to their right goaL Fibres from the' nerve cells bf the brain might thus grow down to the new body; fibre froin the' nerve cells bf-the body might grow up into the new head.
But are wc tb. assign thc ßame power of selective- union to the other tissues?, "Will'the" skin join thc -skin, the gullet
join the gullet, the torn muscles acquire ' pew insertions? lt is to be remembered -that the living .tissues vt the neck will shrivel almost in the moment of cutting, shrivel, moreover, in different fashions .according Ito their texture.,, In ^plastic opération on' the'huihán: body the sepá- rate tissues have each to be stretched and ligatured in their, proper positions. There ia jio suggestion as to how this was accomplished in. the experiniente; indeed, "the- impression is given that it was "found enough simply to apply: the! one cut Bürface to.the other. And there is thc further - difficulty bf the blood channels and the tracheae; the body, no doubt, could live on its own resources "for a considerable time, but the head requires a suppl»' of blood anjî^oxygen
from the body.
Transplantation of. Tissues. .."
Hitherto the difficulties raised have been surgical, and phvsiologîcal. They apply to all the cases, but there Í6 a fur- ther 'difficulty which applies only to the more startling cases, air. Finkler re- ports success in grafting the head bf one species ofbutterny on the body of
another, and in other Cases from one ? genus to another. Now. this is. opposed to the trend .of experimental results .in man - different branches' of the animal kingdom. Grafts between, thc tissues bf alien. bodies have sometimes an initial
success, but later" on, whether the alien ,
tissue be a graft or a transfusion,/t is treated: as a foreign-substance, and is; absorbed, ejected, or eücapsulcd.1 Still' more often, especially In the case of transfusion, the alien tissue or fluid be- haves ns'-aii active' poison; The result
is not success, but death of the graft . and of the host- Some Of these Vienna experiments, if confirmed, will therefore be in opposition to what has become almost on.accepted principle in biology, the mutual repugnance of. alien '.living
tissues. ; .