CYTOLOGY OF ANISOLABIS MARITIMA BON. 
237 
Embryos were removed from their chorionic coverings before 
fixation in Flemming^ s fluid. 
The abundance of material, the large number of preparations 
made, and the variety of methods employed lead the author to 
believe that his results are fairly accurate. 
All drawings were made with the aid of a camera lucida, using 
a 1.5 mm. Zeiss apochromatic objective and a 20 X compen- 
sating ocular. This gave an initial magnification of 3300 
diameters. The drawings were reduced in the reproductions, 
plate XXIV about one-third and plates XXV and XXVI about 
two-fifths. 
4. THE GONADS 
Each testis consists of two long narrow tubules surrounded 
by a fat sheath. The length and narrowness of the tubules 
gives a good seriation of stages from the blind tip to the bottom 
where the sperm pass into the vas efferens. Near the blind or 
cephalic end of the tubule is a large apical cell, surrounded by 
young cysts of spermatogonia. These younger spermatogonial 
generations are larger cells and better for spermatogonial counts 
than those in cysts more caudad. The cysts are clearly marked 
off from one another by distinct walls. The spermatocytes 
undergo considerable growth in size and their cytoplasm acquires 
a large amount of mitochondria. The spermatocyte cysts occupy 
by far the greater part of the tubules in nymphal males. At 
no time during the growth period do the chromosomes disappear 
or lose their staining powers. The transition from ultimate 
spermatogonia to. the formation of the spermatids must be rather 
slow, inasmuch as every stage in the conjugation of the chromo- 
somes and the formation of the tetrads may be found in the 
testes of a single nymph, previous to the final moult. This is 
in marked contrast to many insects, in which the syndetic stages 
are very rare and difficult to find. One fortunate condition in 
the study of Anisolabis is the fact that each testicular tubule 
contains a large number of cysts and that each cyst shows slight 
variations in its meiotic phase. 
