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SUMMARY OF CURRENT RESEARCHES RELATING TO 
it is interesting to note, observable also in the spermatozoa of the Locus- 
tidae, which are of the filiform type ; for, in them, there is a cap and 
head of similar origin, and a single caudal filament which is derived 
from the cytoplasm. After briefly summarizing the very divergent 
views of Schweigger-Seidel and Biitschli, the author explains that the dif- 
ferences are due to the fact that the spermatozoon is a modification of the 
cell which may present a more varied morphology than is generally 
supposed ; but he is content for the present to promise to prove this 
proposition. 
Our knowledge of the habits of the higher Crustacea is so imperfect 
that it is difficult to give any answer to the question, what is the aim 
of the remarkable cellular transformations that occur. It is, indeed, 
probable that in most of them fecundation is external ; if so, we may 
presume that the male elements are provided with stiff points as fixing 
organs or hooks, either to seize on the filamental abdominal appendages 
of the female, or on the surface of the ova. It is to be especially noted 
that it is in toe Macrura and Carida that the radial filaments are 
long, fixed, and resisting; in the Brachyura, where the abdomen is 
so folded on the thorax as to form a kind of chamber in which the 
spermatozoa can be retained, the radial filaments are feeble or even 
absent. 
The modifications of the primitive nucleus and the rise of the 
secondary one may be due to an early differentiation, the object of which 
was to make the two nuclear elements, which are found in the nuclei of 
most cells, independent of one another. If this be so the male repro- 
ductive cells of decapod Crustacea may be referred to the primitive 
type of the ciliated Infusoria. 
Physiology of Decapod Crustacea.* — M. L. Cuenot has a prelimi- 
nary notice of the results of his physiological studies, which have been 
chiefly made with Astacus fluviatilis. The process of excretion has been 
studied by the injection of various colouring matters into the coelom of 
vigorous animals. The green glands and the branchial glands are both 
organs of excretion. The two divisions of the labyrinth of the former 
excrete a certain number of substances, such as acid fuchsin, saffranin, 
vesuvin, &c., but indigo is only eliminated by the green portion, and 
helianthin only by the white ; this shows that the two parts of the 
labyrinth have different functions. The whole of the labyrinth has a 
strong alkaline reaction, but the second is distinctly acid, and eliminates 
various substances. 
The branchial glands, which the author was the first to describe, are 
so disposed that the blood is forced to pass between their cells. They 
are made up of cells, with one or several nuclei, which contain products 
of katabolism identical with those in the cells of the saccule. Their 
action on colouring matters is exactly that of the saccule, and they have 
an acid reaction. They have no excretory canal, but it is probable that 
they have a function comparable to the liver of Vertebrates, for there 
is no doubt that they form carcinuric acid. But these branchial glands 
have also a function in the process of phagocytosis, so that they are 
exactly comparable to the cells of Leydig in Gastropods. 
* Arch. Zool. Exper., i. (1893) pp. xxi.-iv. 
