704. 
scarcely permitit. Those who may be interested 
in the subject are at liberty to make such in- 
quiries of the writer as they see fit. Suffice it to 
say that in a country like our own, well tray- 
ersed by water ways, a marine laboratory 
capable of rapid locomotion, at an exceedingly 
small cost, seems a very desirable adjunct to 
true university workin natural history subjects. 
G. D. HARRIS. 
CORNELL UNIVERSITY. 
SCIENTIFIC LITERATURE. 
Ueber Verwachsungsversuche mit Amphibienlarven. 
Von Dr. G. Born. Leipzig, W. Engelmann. 
1897. (Reprinted from Archiv fir Entwick- 
elungsmechanik, Band IV.) 8vo. Pp. 224. 
Pls. I.—XI. 
Professor Gustow Born is distinguished among 
living morphologists for the novelty and thor- 
oughness of his investigations. It is to him 
that we owe the section modelling which is 
now so much used for the anatomical recon- 
struction of embryos, and which he has himself 
applied with brilliant results to the study of the 
development of the thyroid and of the heart. 
To him we owe also the experimental demon- 
stration of the isotropism of the egg. In the 
present work we encounter again striking origi- 
nality of method, coupled with extraordinary “ 
patience and thoroughness in the execution of 
the research. The method consists in the arti- 
ficial union of two amphibian larvee ; this is ac- 
complished by making a smooth cut on each 
larva, adpressing the two cut surfaces and al- 
lowing them to grow together; the natural 
fusion begins in half an hour to express itself 
and is complete in a few hours; in successful 
cases the united pair develop in unison and re- 
main alive for weeks. Dr. Born’s patience 
shows itself in the number and variety of 
fusions accomplished and in the exhaustive an- 
atomical study of the developed monstrosities. 
The only earlier experiments on fusion of two 
individuals were those of Trembley on Hydra, 
recently repeated by G. Wetzel. On the other 
hand, the announcement of Born’s results has 
already occasioned a number of similar experi- 
ments on other animals. W. Roux appears to 
have first discovered the extraordinary power 
of the eggs and young laryee of frogs of with- 
- SCIENCE. 
[N.S. Vou. VI. No. 149. 
standing severe mechanical injury, and others 
have demonstrated the wonderful regenerative 
faculty of Amphibia during the early stages. 
Born has taken advantage of these characteris- 
ties to secure the concrescence of two individ- 
uals which develop afterwards as one. The 
spread of the ectoderms is the first step of the 
union, and there isin a short time a complete 
sheet of this tissue, with no visible break or trace 
of demarcation, extending from one larvee to the 
other and covering the wound. This healing 
over iseffected by the expansion of the sheet of 
ectoderms, and this expansion is not due to mul- 
tiplication of the cells. Most of Born’s experi- 
ments were made on larvee of four millimeters 
(more or less) in length and on the following 
species: Rana esculenta Bombinator igneus and 
Pelobates fuscus; the larvee of toads and of Rana 
fusca proved less favorable. Pieces of almost any 
size can be made to unite either of the same, or 
of different larvee, and even of laryze of two 
species. When the experiment succeeds such 
united pieces will live for about three weeks, or, 
in other words, until the supply of yolk material 
for the maintenance of growth is exhausted, but, 
if one or both the pieces have a digestive tract 
with mouth and arms, the united pieces may 
continue to develop indefinitely, and in such 
cases the blood channels of both species acquire 
open communication with one another, so that 
even when there is but one heart the blood cir- 
culates through both components. During the 
life of the fused larvee, their development, their 
differentiation proceeds, each organ continues 
its progress. The development essentially fol- 
lows the principles of Roux’s mosaic theory. 
The following schedule indicates the variety 
of successful unions accomplished by Professor 
Born: 
A. Experiments on single larvee. 
‘1. Pieces cut off and allowed to continue 
their development. 
2. Larva cut through and the pieces re- 
united. 
B. Fusion of two larvee, or parts of two larve. 
1. Both larve of the same species. 
a. Fusion of anterior with posterior pieces. 
b. Fusion by the ventral surfaces. 
c. Fusion of the posterior piece of one 
larva with the ventral side of another. 
