ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
201 
of this genus is remarkable for the presence of branchiae, which are 
attached a little below the lateral setae ; and in Branchiura they are 
limited to the tail end of the body. 
Structure of Enchytrseidae.* — Dr. R. Hesse has found two new 
littoral Enchytraeids at Naples, for one of which it is necessary to 
establish a new genus, which may be called Parenchytrseus (P. litteratm ) ; 
the other may be called Pachydrilus litoreus. A careful study has been 
made of the musculature, with the result that it has been discovered that 
all of it, with the exception of the exterior portion, consists of muscle- 
cells, which belong to the Nematoid type. The septal glands appear to 
have the function of secreting an adhesive material. Special glands have 
been observed in those segments which succeed the genital segments ; 
these glands have no lumen, but form essentially a bundle of unicellular 
glands with separate efferent ducts, which traverse the cuticle ; they are, 
in fact, hypodermic cells modified for some special purpose. This pur- 
pose appears to be the secretion of a material which binds the worms 
more closely together during copulation, and we may therefore call them 
copulatory glands. 
In conclusion the author has a note on the so-called enteric blood- 
sinus ; he thinks that instead of speaking of a sinus supposed to be 
formed by the outgrowth of the enteric epithelial layer and the exterior 
muscular layer, we ought rather to consider that we have to do with a 
vascular plexus which extends over the intestine, and which is Com- 
parable to that of Dero and some Naids, although not so well developed. 
0. Nemathelmintlies* 
Experiments with Ova of Ascaris.j — Dr. L. Sala has observed the 
effect of cold on the maturation and fertilization of the eggs of Ascaris 
megalocephala. The living worms were enclosed in a glass, and this was 
placed in a freezing mixture, at a temperature of -(- 3° to — 5° C., for 
periods varying from half an hour to two hours. Thereafter the glass 
was gradually restored to a temperature of 16°-18° C., and afterwards 
raised to 20°-30° C. for a day or two. Among the consequences of this 
treatment, the following phenomena were frequent. Polyspermy often 
occurred. The yolk-substance was slightly affected, appearing, for 
instance, more vacuolated than is normal. The egg-membrane became 
soft and viscid, and eggs fused together into strange double forms. 
Sometimes the number of chromosomes was increased, sometimes it was 
decreased ; their form and arrangement was also altered. The typical 
spindle-like arrangement of the achromatin substance of the directive 
spindle was more or less altered, and replaced by a variety of compli- 
cated and often remarkable forms. Not unfrequently only one polar 
body was formed, and in many cases the formation was abnormal. In 
consequence of such modifications as the above, others occurred in the 
formation of the ovum-nucleus, sperm-nucleus, and segmentation- 
nucleus. In one case as many as six centrosomata were seen in the 
fertilized ovum. 
* Zeitschr. f. wise. Zooh, Ivii. (1893) pp. 1-17 (1 pi.). 
f SB. K. Preuss. Akad. Wiss., 1893, pp. 657-74 (1 pi.). 
1894 p 
