EMBRYOLOGY OF COCCIDS 75 



Brandt ('89), who likewise studied Lecanium hesperidum and 

 Aspidiotus nerii, with special reference to the embryonic cover- 

 ings, stated that the embryo of Aspidiotus nerii was bent, as 

 Mecznikow had already described, with its caudal part over the 

 oral portion. He further observed the process of the revolution 

 of the embryo following the rupture of the amnion. In Aspidi- 

 otus, he observed, as did also Mecznikow, that the ventral plate 

 of the embryo was found lying closely on the amniotic covering, 

 even before the revolution, so that the yolk was rapidly removed 

 from this region. 



Then followed the work of Putnam (78) on the cottony maple 

 scale, Pulvinaria innumerabilis. This writer evidently thought 

 the ovarian eggs were in some manner, unknown to him, attached 

 to the body cavity by their free or anterior end, where the dif- 

 ferentiation first takes place. Besides this mistake, his figures 

 are too vague to show anything very definite. However, this 

 much was sure, that the eggs of the cottony maple scale developed 

 within the body of the female. He detected the presence of the 

 pseudonavicellae in the female before mating and also in the 

 older eggs. The method of infection or the possible migration 

 of these bodies into the eggs was not studied. However, he 

 suggested that these bodies, having higher specific gravity than 

 water, may represent the metamorphosed state of spermatozoa, 

 and that their presence in the egg may be comparable to the 

 phenomenon of fertilization. 



Witaczil's ('86) work on the anatomy of the coccids contains 

 an account of the differentiation of the nurse cells and of the egg 

 cell from undifferentiated epithelial cells in the ovaries of Leucaspis 

 pini. Although not figured, there is an account of the presence 

 of the so-called nutritive string between the nurse chamber and 

 the egg chamber. He did not find the pseudovitellus in the eggs 

 of several species, but expressed the view that the pseudovitellus 

 of Mecznikow may represent a mass of yolk granules. 



The investigations above mentioned were entirely made upon 

 fresh material or at least upon material prepared in toto. The 

 eggs were usually studied in water to which acetic acid and sugar 

 were added, or in somewhat similar solutions. The only paper. 



