144 BIOLOGICAL LECTURES. 



Tachygenesis as a working theory, it is obvious that these 

 exceptional or abbreviated processes can be considered as due 

 to that law, since it works in the same peculiar way some- 

 times with simple and straightforward exactness, but often also 

 with a complex of introduced characters that make its transla- 

 tion very difficult. 



A large amount of time has been wasted in useless efforts 

 to solve problems of phylogenesis by the aid of the embry- 

 ology of highly specialized and highly tachygenic forms. 

 These may sometimes throw light astern on their own imme- 

 diate ancestry, but are often too deficient in genetic recapitula- 

 tion to be used even in this limited way, and are worse than 

 useless in the solution of problems of phylogenesis in which 

 other genetic series are concerned. Examples of this class are 

 numerous, and almost every embryological work abounds with 

 misdirected efforts to use the early stages of such animals 

 either for or against opinions and theories where their bear- 

 ing has little or no value. This is particularly evident when 

 they are used to show that there are no positive general cor- 

 relations between the ontogeny and phylogeny, or when they 

 are spoken of subjectively as "falsifications" of the embryo- 

 logical record, as if nature were playing a game of bluff with 

 scientific observers. 



This law also forbids the drawing of general conclusions 

 from haphazard investigation, however numerous, broad, and 

 widespread the facts may be, and is consequently opposed to 

 prevailing statistical methods. These assume that, if a large 

 number of embryos be selected at random, the conclusion 

 drawn from their investigation would correct the discrepancies 

 and errors due to what is called insufficient data. The error 

 in such an assumption is that, while statistics apply, if care- 

 fully used, to a multitude of living forms of the same stock 

 (and one may safely trust them perhaps in the general meaning 

 of a character among animals of the same age or the same 

 grade), it does not apply to phylogenetic relations of animals of 

 different grades. The relations of these being serial, all obser- 

 vation of a statistical kind covering animals of different grades 

 must be arranged and compared upon the same basis. It seems 



