1914] The Egg-Laying Habits of Plethodon Cinereus. 123 



of them were suspended. Evidently under the somewhat unnatural 

 conditions the female had moved after the extrusion of each of the last 

 five eggs. Case III. In picking apart a decaying log there were exposed 

 on one occasion a female and four eggs. One of these lay by itself, 

 markedly elongated ; the other three were in contact, two of them some- 

 what elongated, the third apparently spherical. All four were lying on 

 the floor of the cavity, which fortunately had been opened from the side. 

 Examination of the female revealed the existence of four eggs in the 

 posterior parts of the oviducts. Evidently the egg-laying process had 

 been interrupted by the opening up of the nesting-chamber. 



These last two cases have been selected from among a few of the same 

 general character because they differ from the rest in that the eggs were 

 not suspended. In opening up logs a few clusters have been found un- 

 attached. At first, in such cases, it was taken for granted that the open- 

 ing up of the nesting-chamber had involved the loosening of the eggs. 

 Since attention has been directed to the possibility of a cluster not having 

 been attached, two such have been found under circumstances that 

 would seem to preclude the idea of their having been torn from their 

 attachment. In neither of these two cases could a stalk attached to the 

 cluster be found. It would seem that occasionally the tendency to 

 reduce the amount of material devoted to forming stalks for the eggs 

 goes so far as to eliminate even the stalk of the first egg. No exact 

 count has been kept of the number of such cases as compared with the 

 normal, attached ones, but the impression left is that it is very small. 



As might be concluded from Case 7, an examination of the relation 

 of the stalk to the eggs shows that it does not come from any one parti- 

 cular egg, but from a quantity of mucus that adheres to the outer en- 

 velope of certain of them; the impression given is that of a material 

 poured onto the bunch, part of it being drawn out to form the stalk. 

 As is the usual case among Urodeles the outer envelope of each egg is of 

 a much more sticky mucus than the inner ones. Plethodon is peculiar 

 in having this outer layer unusually thin, and in depositing a still more 

 sticky mass of mucus before the egg-laying proper begins. 



In most amphibia the impulse toward the deposition of the eggs, 

 once these are ready for the act, is an imperative one. In some cases 

 (e.g., many frogs) the assistance of the male is needed, but generally 

 speaking, when the proper time comes the spawn will be deposited even 

 with conditions and surroundings that are far from natural. Both Rana 

 pipiens and Rana catesbiana that have been kept over winter, without 

 feeding, in a tank in the basement of the Biological Building of the 

 University, have been known to spawn in spring and early summer 

 respectively. (Such spawn has never developed, evidently has never 



