Miscellaneous. 
241 
In order to make cross sections of the germs and embryos thus 
extracted from the ovum, I leave them for some days in Muller’s 
liquid, and colour them with picrocarminate of ammonia. After 
depriving them of water by treatment with alcohol of spec. grav. 
0828 and then with absolute alcohol, I put them for 24 hours into 
collodion. The embryo is then arranged upon a small slab of elder- 
pith soaked with alcohol, and covered with a layer of collodion. 
When the collodion has arrived at a suitable consistency, very thin 
sections may be made, including the embryo and the plate of pith ; 
and these are to be preserved in glycerine. 
This process is applicable to all sorts of embryos which are not 
very thick, so that they may be coloured en masse. It has the 
immense advantage of enabling one to see at what level in the 
embryo each section is made, to preserve each section in the midst 
of a transparent mass, which sustains all the parts and prevents their 
being damaged, as too often happens when an inclusory mass is 
employed from which the section must be freed before mounting. 
In his 4 Precis de Technique microscopique,’ M. Mathias Duval 
has already recommended collodion in embryological researches, but 
without indicating his mode of employing it. We hope to be ser¬ 
viceable to embryologists by making known to them a process which 
they may find useful.— Ball. Soc. Phi lorn. Paris , November 22,1878. 
On a Gigantic Isopod from the Great Depths of the Sea. 
By M. A. Mit.ne-Edwauds. 
The Government of the United States has repeatedly caused dredg¬ 
ings to be made in the American seas ; and recently it commissioned 
Mr. Alexander Agassiz to explore the bed of the Gulf-stream in the 
Straits of Florida, between the southern point of that State and the 
island of Cuba. In December 1877 that naturalist embarked on 
board the steamer 4 Blake,’ and made a series of dredgings, some of 
which were carried nearly to 2000 fathoms, and brought up a con¬ 
siderable quantity of animals. Mr. Agassiz, with the consent of the 
administration of the Coast Survey of the United States, has 
sent me all the Crustacea collected during this cruise, and begged 
me to investigate them. The collection is very extensive and rich ; 
it will furnish me with the materials for a memoir, of which I 
shall have the honour hereafter to communicate to the Academy 
the general results. At present I shall confine myself to calling 
attention to one of the most extraordinary animals for which I am 
indebted to Mr. Agassiz, namely a gigantic Isopod, dredged at 955 
fathoms, to the north-east of the bank of Yucatan, north of the 
Tortugas *. 
This Isopod, to which I have given the name of Bathgnomus 
giganteus, is remarkable not only for its comparatively enormous 
* See, on this subject, A. Agassiz, Letter No. 1 to C. P. Patterson, 
Sup. Coast Survey, on the dredging-operations of the U.S. Survey steamer 
4 Blake ’ during parts of January and February 1878 (Bull. Mus. Comp. 
Zool. Cambridge, vol. v. p. 4). 
Ann. cfr Mag. N. Hist. Ser. 5. Vol. iii. 16 
