No. 2.] THE DEVELOPMENT OF THE NEWT. 279 



the laying season, amounting possibly to one-fourth of the total 

 weight. This may be partly due to the not inconsiderable 

 amount of substance that goes to form the protective membrane 

 of the t^g, and partly to the conversion of body-substance 

 into yolk during the laying season. One might be tempted 

 to explain this loss of body-weight by increased katabolism 

 of the tissues, due to higher temperature, were it not for 

 the fact that the males, although strikingly thin and ex- 

 hausted at the end of the period of ^^ Liebesspiel,'' gain 

 rapidly in plumpness and weight as the summer advances. 

 The true explanation seems to lie rather in the directions first 

 indicated. 



Transformatiojis, etc. — Gage ('9i) in his recent interesting 

 paper, describes and figures the external developmental stages 

 that the newt passes through, and arrives at the important con- 

 clusion that the well-known red, terrestrial form — the so-called 

 variety miniatiis — is merely a stage in the life-history of the 

 species, and is not to be regarded as a distinct variety. Al- 

 though I have not had these animals under observation long 

 enough to warrant me in expressing a very decided opinion on 

 this point, I feel fairly confident, from what I have seen, that 

 Gage's main contention is correct. One of the first things that 

 strikes the collector of the aquatic form is the comparative 

 absence of all newts below a certain general grade of develop- 

 ment. These young and immature individuals are not to be 

 found in water, by using a net with finer meshes, but may be 

 discovered on land by turning up the stones and logs on the 

 shores of the pond, and one is hence tempted to infer what Gage 

 has concluded, viz. that the red, terrestrial form is merely an 

 immature condition of the common aquatic newt. Gage has 

 given us an interesting discussion of the causes that may have 

 led to this curious change of color and habitat. 



I do not yet feel prepared to say that I regard the assumption 

 of the terrestrial habit as a necessary stage in the development 

 of every individual. It is quite possible that certain individ- 

 uals attain maturity without ever leaving the water, although 

 perhaps the great majority of newts pass their Wanderjahre on 

 land. 



