270 



PROCEEDINGS OF THE ACADEMY OF 



macrocosm is a parallel or rejietition of the microcosm in matter and mind. 

 As the development of the individual, so the develoiiment of the genus. 

 We may add — so the development of the whole of organized beings. 



These metamorphoses may be fitly compared to those in the molecular con- 

 stitution of matter. The force of cohesion belvreen the atoms of a vapor 

 steadily increases with descending temperature, and in a regular ratio, till a 

 given point is reached, when a sudden metamorphosis to a denser, or liquid 

 condition takes place. Nor have we reason to believe, with regard to many 

 substances, that there is any parallel relation between the temperature and 

 the molecular constitution before or after the metamorphosis takes place. 

 So the temijei'ature continuing to descend, the molecular character of the 

 liquid remains unchanged until the vis conservalrix suddenly giving way at the 

 ordained point, a solid is the result. Thus while the change is really jirogress- 

 iiig the external features remain unchanged at other than those points, which 

 may be called expression points. 



Now the expression point of a new generic type is reached when its appearance 

 in the adult falls so far prior to the period of reproduction as to transmit it to 

 the offspring and to their descendants, until another expression point of pro- 

 gress be reached. 



Thus a developmental succession does not so obliterate the lines drawn 

 around nature's types as to render our system ineffectual as an expression of 

 them. 



The successional acceleration or retardation in metamorphosis may be best 

 illustrated in the cases selected above, by the following tables. These are 

 taken, it will be remembered, from the Bufonida? and Hylid»e as examples of 

 " exact parallelism ;" three are now added from the Rauida3 and Discoglos- 

 sidte. The case of ''inexact parallelism" is that of the Scaphiopodidas. 



Whether they are cases of acceleration or retardation can only be deter- 

 mined by reference to the i)ala;ontology of the respective groups, or a careful 

 comparison of times of metamorphosis. In the case of the Discoglossidse I 

 suspect it to be retardation, as the highest genus is extinct. The others I 

 shall arrange with them for temporary convenience. Were I dealing with a 

 group of Ganoids, I should imagine the process to be retardation, as this 

 group is going out of existence. On the other hand, were they higher 

 Oscine birds we might imagine the case to be reversed. 



TABLE I. 



Series No. 1. No. 2. No. 3 



BombJnator..Hyla Epidalea. 



Alytes* 



Discoglossus 



Sey topis Bufo sp. 



Osteocephalus Bufo sp. 



Latonia Trachycephalus.... Peltaphryne- 



* Aparotoid gland of small size is added here, but is not generic as compared with Bom- 

 biaator, as the latter has collections of crypts on the same region and over the body. 



[Oct. 



