JULY 1899] FRESH FACTS 61 



by secreting an oily substance which keeps the water out of the respiratory 

 reservoir under the elytra. The defensive apparatus of which Bordas speaks 

 is the rectal pouch. 



Freezing Eggs without killing them. Etienne Rabaut. " De l'influ- 

 ence de la congelation sur le developpement de l'oeuf de poule," Comptes 

 Rendus Ac. Sci. Paris, cxxviii. 1899, pp. 1183-1185. Continuing experiments 

 begun by his master, the late Camille Dareste, Mr. Rabaut finds that eggs 

 exposed for half an hour in a freezing mixture at - 15° C. are not killed. 

 Lasting perturbations are induced, and after warming (quickly or slowly) most 

 of the eggs show in three days a proliferating blastoderm spreading over the 

 yolk, but without trace of embryonic differentiation. Some showed abnormal 

 embryos, and a very few — proving the individuality of the egg — were normal. 



A Sexual Peculiarity. A. Kowalevsky. " Quelques mots sur YHaemen- 

 teria (Clepsine) costata," Comptes Rendus Ac. Sci. Paris, cxxviii. 1899, pp. 1185- 

 1188. In this leech there is marked protandry, and exchange of spermato- 

 phores occurs between the male organs at a period when the female organs are 

 still rudimentary. Kowalevsky believes that the same phenomenon will be 

 found to occur in other Hirudinea, such as Piscicola, the fish-leech. 



Egg within Egg. Francis H. Herrick. " Ovum in Ovo," Amer. Natural. 

 xxxiii. 1899, pp. 409-414, 3 figs. The occurrence of an egg within an egg is 

 not a fresh fact, but it is often supposed to be. Mr. Herrick classifies the 

 cases on record in two sets : — (i) enveloping egg usually normal, but occasion- 

 ally of large size ; blastoderm recorded in at least one instance ; (ii) enveloping 

 egg of colossal size, complete, with blastoderm probably present. One inter- 

 pretation, which covers a number of cases, supposes that the small included egg 

 represents a fragment of a normal ovum which has been ruptured in the upper 

 part of .the oviduct, or at least after the first layers of albumin have been 

 added to the normal egg. It is possible that any substance which serves as a 

 local stimulus to the upper part of the oviduct, whether coining from the ovary 

 as abortive egg or egg-fragment, or from the duct as secreted product, may 

 serve as a nucleus about which an egg-like body may be formed. Various 

 inclusions which are not true eggs at all may be taken up by the egg and im- 

 bedded in it. But in other cases, such as double or triple yolk eggs, we have 

 to deal with a fusion of the albumin in two or more ova, which are treated in 

 the uterus as one egg and surrounded by a single shell. This process may 

 sometimes be complicated by the inclusion of a third egg of normal size and 

 already covered by a hard shell. 



Excretion in Molluscs. L. Cuenot. " L'excretion chez les mollusques," 

 Arch. Biol. xvi. 1899, pp. 49-96, 2 pis. The injection method of studying the 

 excretory function has led Mr. Cuenot to conclude that there are three seats of 

 the process in molluscs : — (a) the nephridia, (6) closed cells isolated in the 

 connective tissue or concentrated in the vicinity of the heart, and (c) in 

 gasteropods, certain cells of the liver. 



Cephalic Eyes of Bivalves. Paul Pelseneer. " Les yeux cephaliques 

 chez les Lamellibranches," Arch. Biol. xvi. 1899, pp. 97-103, 1 pi. Pelseneer has 

 now published a fuller account of the discovery, to which we previously referred 

 {Nat. Sci. xiv. 1899, p. 6), and has given a plate. To what was then reported, 

 we may add Pelseneer's note that the larval eye was seen in Mytihis and other 

 forms by Loven (1848), and in Mytilus by Wilson [Fifth Annual Rep. Fishery 

 Board of Scotland). Pelseneer has shown its persistence in various adults. 

 As there was a misprint in one of our previous sentences, we may further note 

 that the eyes do not make their appearance in Mytihis until after the formation 

 of the first branchial filaments. 



