No. 2. ] ANURIDA MARITIMA. 241 
Nutritive Cells. 
The possession of nutritive cells is a character widespread 
among the Insecta. In the majority of cases, ova are associated 
with a definite number of cells that assist to a greater or less 
degree in yolk formation and in the general growth of the ova. 
Korschelt ('g6) divides insect ovaries into two classes, according 
to whether they possess these accessory cells in the form of a 
nutritive chamber or otherwise. Sometimes they are arranged 
in separate chambers lying between the eggs, and sometimes in 
a terminal chamber. Many curious forms are described by 
different writers. Claus (64), using Coccus and Aspidiotus, 
found “yolk strings” leading from nutritive cells to the egg, 
in some cases passing through the chamber of an undeveloped 
egg, The same structure, a “ Dottergang,” is described by 
Wielowiejski ('85) in Pyrrhocoris. Sometimes the nutritive cells 
are arranged in a highly developed follicle and absent in any 
other form. Korschelt (86) figures Vanessa urticaria as pos- 
sessing a few such cells, closely applied to one surface of the 
egg, an arrangement resembling that found in Anurida. Among 
the Apterygota, Grassi (gs) figures Campodea alone as having 
anything similar to nutritive cells; here, as shown (Fig. VI), they 
are interpolated in chambers between the eggs. He expressly 
states, however, that the nutritive cells are zo¢ homologous with 
those of the Insecta; why he does not say, unless he wishes to 
consider the ovary as not the morphological equivalent of the 
ovariole of the higher Insecta. In the thysanuran (Zomoceras 
sp.?) nutritive cells were found closely similar to those described 
for Anurida, but smaller and arranged more distinctly as a fol- 
licle and present in larger numbers (Fig. 14). In Anurida, as 
before described, each egg is associated with its string of 
nutritive cells, varying in number from five to eight. Will 
(84, ’85) gives the results of his studies, and presents in full 
his idea of the compound origin of an egg, and the formation 
by the egg of some of the follicle cells. As he has, however, 
changed some of his recent statements of the case, these studies 
will not be mentioned in detail. 
