634 J. T. PATTERSON 
segmentation of the egg. Furthermore, he points out that the 
early blastomeres of the egg of Crisia are separated from each 
other by follicle-tissue, and that they are surrounded by a rich 
nutritive material, which is obtained through the protoplasmic 
strands connecting the several units of the colony with the ovi- 
cell. He believes that the production of numerous larvae from 
the primary embryo in Crisia is a process comparable to arti- 
ficial blastotomy in Echinus eggs,as shown by the experiments of 
Driesch (’92). His general conclusion is clearly stated in the 
closing paragraph of his paper. He says: 
The cases already quoted may be taken as showing that some of the 
abnormalities in the development of Crisia may be due to the nutritive 
conditions in which the development takes place. Just as the presence 
of food-yolk within the egg modifies the character of the segmentation 
and the formation of the layers, so the presence of copious stores of nu- 
trient material in the maternal tissues outside the egg may also effect the 
early developmental processes. Thus the large number of relatively 
large larvae which develop from the minute egg of a Crisia could not be 
produced if the egg were not supplied with nutriment from outside it- 
self. While some of the irregularity in the segmentation of the egg may 
be due to this cause, the extreme independence of the blastomeres at an 
early stage may be connected with the acquirement by the embryo of a 
habit of forming buds in the embryonic condition. 
Marchal (’04) has expressed somewhat similar views, as may 
be gathered from the following quotation." 
As to the determining cause of the division of the germ, Marchal 
thinks that it is from the sudden surrounding with more dilute liquids in 
the interior of the nourishing mass and in a concomitant modification of 
the osmotic exchanges in the interior of the cellules. One sees, in 
fact, with Encyrtus that polyembryony reaches its greatest intensity at 
the moment when the larvae of the Hyponomeuta commences to feed 
(in the early days of April), and for the Polygnotus at the period when 
the young larva of the Hessian fly engorges itself with sap. Now, the 
production of the rapid changes bringing about osmotic pressure con- 
stitutes precisely the procedure employed to bring about the separation 
of the blastomeres and their evolution into several distinct individuals, 
is eee been shown by the experiments already mentioned of Loeb and 
ataillon. 
19 oes Git. py Zab: 
™ From Howard’s (’06, p. 816) clear translation of Bugnion’s (’06) review of 
Marchel’s (’04) paper. 
