Decembeb 21, 1906.] 



SCIENCE. 



815 



'The larva of Plusia parasitized by the Liio- 

 'ma^tix lives in summer three or four days 

 longer than the healthy larva and reaches a 

 greater size. 



Each generation of the Plusia corresponds 

 to a generation of the Litomastix. 



The maturation of the egg is identical with 

 ^fertilized and unfertilized (parthenogenetic) 

 individuals. In the development of the egg 

 of the Litomastix we have a process of germ- 

 inogony or specific polyembryony, quite dif- 

 :ferent from that found by Marchal in Encyr- 

 ■ius fuscicollis and Polygnoius minutus. 



From one egg of Litomastix there originate 

 fibout a thousand sexual larvae and some hun- 

 dred or more asexual larvae. The first trans- 

 form into adults, while the second are de- 

 stroyed, serving probably as aids to the sexual 

 larvae in lacerating the internal organs of the 

 liost larvae. 



Asexual larvae are notable from their form, 

 in the structure of the exoskeleton, and by the 

 lack of a circulatory system, of a respiratory 

 system, of the malpighian tubules, and, above 

 all, of the reproductive system. 



Each crnbryo of the sexual or asexual larva 

 is surrounded by two involucres, of which the 

 external one is derived from the ooplasm and 

 the polar nucleus; the internal from a layer 

 of cellules derived by delamination from the 

 embryonal morule. 



The fecundation of the egg with Litomastix 

 •determines the female sex. 



And now, what are the broad bearings of 

 ihis interesting work? 



Giard had already in 1898, in his note cited 

 above, in discussing the value of Marchal's 

 ■discovery as announced in his preliminary 

 note, stated that if one wishes to seek in other 

 classes of animals embryonic peculiarities 

 -comparable to those revealed by Marchal, it is 

 perhaps in the degraded platyhelminths of the 

 ^families Orthonectidae and Dicyemidse that 

 :Something analogous may be found. The 

 sporocysts of Bhopalura are in effect, he 

 •stated, filled with embryos by a process of 

 ovular multiplication which is not unlike that 

 which takes place in the embryonal tubes of 

 dhe Encyrtus. 



Marchal himself publishes an important 



section entitled ' Relations existing between 

 Specific Polyembryony of the Hymenoptera 

 and Other Modes of Agamic Reproduction.' 

 These instances are well summed up by Bug- 

 nion in a paper entitled ' La Polyembryonie 

 et le Determinisme Sexuel ' (Bulletin de la 

 Societe Vaudoise des Sci. Nat., XLIL, No. 

 153, March, 1906), in which he also includes 

 a consideration of certain additional observa- 

 tions, and we may adopt in a very free trans- 

 lation Bugnion's summary: 



Other examples taken from the whole range 

 of the animal kingdom somewhat approach the 

 polyembryony of insects. 



With the cyclostomes (Bryozoa) one finds a 

 budding which takes place in the egg at the 

 beginning of development. In the genus 

 Lichenopora this budding is replaced by the 

 dissociation of the primitive embryo into a 

 great number of secondary embryos. We have 

 then here a phenomenon comparable to that 

 which we have seen with the parasitic Hymen- 

 optera. It is necessary to note, however, that 

 the secondary embryos thus formed offer al- 

 ready an indication of embryonic buds, while 

 the morules of Encyrtus or the blastules of 

 Polygnotus present no apparent differentia- 

 tion. With other Bryozoa {Lophopu^, Cris- 

 tatella) there is also to be seen a budding in 

 the egg, but this takes place at a later period. 



With the worms, Kleinenberg announced in 

 1879 the curious case of Lumhricus trapezo- 

 ides, in which the egg develops into two em- 

 bryos; here the multiplication takes place by 

 a sort of internal budding intervening in the 

 gastrula stage, at which time differentiation 

 of the buds is already effected. 



With the tunicates, the species of Diplo- 

 soma offer a curious case of precocious bud- 

 ding which gives the appearance of the simul- 

 taneous formation of two embryos in the same 

 egg, but in reality this proceeds from the in- 

 ternal budding of an embryo already differen- 

 tiated (Salensky, Caullery, Pizon, Perrier). 

 With Pyrosoma the budding also takes place 

 in the egg, but by a slower method, and it is 

 only when the embryo is organized that it 

 pushes out a ventral stolon immediately cleav- 

 ing transversely into four buds which each 



