476 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
the shells, and occur also on the appendages. Of the flat cells, each 
forms a thin plate closely adherent to the carapace, and in the centre of 
each there is a large rounded nucleus with one marked nucleolus. The 
cell-substance is coloured a transparent but distinct blue by the dye, 
and immersed in this matrix are a number of round vacuoles which are 
apparently occupied by fluid matter. These give the rose reaction with 
yellow light, which is in the body also given only by the basophil 
granules of the blood-corpuscles. These vacuoles may be the receptacles 
of solid particles which have, by some process, been ingested by the 
cells. The rose reaction is also seen in a substance of the nature of a 
slime which the Daphnia has the power of casting on to its surface. 
This substance has a strong affinity for the methylen-blue dye, and we 
may, under the Microscope, watch the formation of a film, sometimes of 
considerable thickness, over the entire surface of the Crustacean. It 
appears to be a true secretion of the ectoderm cells, for, as it forms, there 
is a distinct diminution in the intensity of the rose reaction of the 
ectoderm cells. 
A parallel case has been observed by Miss Alcock and Dr. Gaskell 
in the Ammocoetes-stage of Petromyzon Planeri , where a slime is formed 
which contains an active proteolytic ferment capable of rapidly digesting 
fibrin in the presence of a small quantity of free hydrochloric acid. On 
the other hand, Mr. Hardy completely failed in demonstrating the 
existence of a slime on the shells of Cyclops. 
There is a general similarity in the behaviour of ectoderm cells and 
blood cells towards microbes ; both discharge a rose-staining substance 
previously stored in their cell-substance. 
Durham has called attention to the slime formed by wandering cells 
in Echinoderms, and Mr. Hardy calls special attention to the fact that 
these cells are loaded with granules. 
Two suggestions may be made as to the way in which the surface- 
slime of animals protects them. It may have a mechanical action ; it 
may be taken for granted that the presence of a film of soluble slime 
on the surface of an animal immersed in water would, like the copper 
sheathing of ships, mechanically prevent the occurrence of parasitic 
growths by continually forming a fresh surface. The slime may, further, 
have a specific poisonous power, mainly, perhaps, against the more minute 
and subtle forms of vegetable parasites. 
Embryology and Metamorphosis of Macrura.* — Prof. W. K. Brooks 
and Mr. F. H. Herrick have devoted much attention to a study of these 
higher Crustacea, the life-history of which is of exceptional value for the 
study of the laws of larval development. An account is first given of 
Stenopus hispidus, the larva of which is, at the time of its escape, a Proto- 
zoea, and it, later on, unites features of resemblance to Lucifer , Sergestes , 
Peneus, and the prawns in general. As in the Sergestidse, the last two 
pairs of “ walking legs ” are shed after the Mysis-stage to be again 
constructed in the Mastigopus-stage. 
A very remarkable account is given of the metamorphosis of Alpheus, 
for it has been discovered that “ while there is such a general similarity 
as we might expect between the larval stages of the different species, the 
* John Hopkins Univ. Circ., xi. (1892) pp. 65-71. 
