544 NATURAL SCIENCE. sept. 



bodies as evidence of this specialised character, and then proceeds 

 to consider to what extent these pecuHar compHcated phenomena 

 are represented in the Protozoa. Of the expulsion of polar bodies, 

 he says that nothing resembling it has ever been observed in any of 

 the Protozoa — an unjustifiably dogmatic statement, inasmuch as 

 portions of the nucleus have been observed to be ejected in the con- 

 jugation of the Ciliata. One of the general conclusions drawn from 

 the discussion is that no line of real demarcation can be drawn 

 between growth and reproduction, even of the sexual kind. But the 

 course of the argument has by no means succeeded in filling up the 

 chasm of difference between the division of one cell into two, which 

 is growth, and the union of two cells into one, which is sexual 

 reproduction. 



The rest of the chapter is devoted to the embryogeny of the 

 Metazoa beginning from the fertilisation of the ovum. In the de- 

 scription of the characters of ova an unfortunate error is made, the 

 pores of the zona radiata in the Mammalian ovum being referred 

 to the same category as the micropyles of other ova. 



The majority of the instances of embryological correspondence 

 described are derived from Haeckel's more imaginative writings, but 

 Mr. Romanes is placidly unconscious that doubt has been thrown on 

 the objective reality of any of them. He does not even quote 

 Haeckel's fascinating, though sometimes unfortunate, speculations 

 with strict accuracy. On one page he figures the gastrula of the 

 zoophyte Gastrophysema, and on another gives two figures oi Prophysema 

 pnmordiale, an extant gastrula-form, all " after Haeckel." As far as I 

 have been able to discover, Haeckel never used the name Prophysema 

 at all. The figures described under this name are copied from those 

 of Halophysema pnmordiale in Haeckel's paper " Die Physemarien," and 

 were proved 12 years ago to represent an organism specially created by 

 Haeckel himself, Halophysema being really a reticularian Protozoan. 

 Gastrophysema was another genus of Haeckel's imaginary extant 

 Gastraea, and I have been unable to discover where among 

 Haeckel's works Mr. Romanes found a reference to the gastrula of 

 a zoophyte called by the same name. 



It is stated thatprobablyall the Metazoa pass through thegastrula- 

 stage, which is correct, if by the latter term is merely meant the 

 diploblastic condition. But only one process by which this condition 

 is reached, namely, invagination, is described, and the gastrula of 

 Olynthus, " after Haeckel," is figured without any mention of the 

 fact that it is not produced by invagination. Another figure is 

 described as the " gastrula of an Arthropod {Nauplius)," as though 

 Nauplius were a genus. 



Still more extraordinary, however, is the foot-note on p. 139, 

 which states that in most vertebrated animals the process of gastru- 

 lation has been more or less superseded by another process called 

 delamination, but that even in the higher Vertebrata embryologists 

 are pretty well agreed as to delamination having been merely a later 

 development of, or possibly an improvement upon, gastrulation. 

 Perhaps the author has , confused Professor Lankester's theory that 

 gastrulation is originally derived from the delamination observed in 

 some Coelenterata, with some faint reminiscence of the modified 

 epibolic gastrulation of fishes and birds. The rest of the chapter is 

 still more strongly permeated with Haeckelism. We have the figure 

 of Haeckel's ideal primitive vertebrate, and two pages of the well- 

 known somewhat ideal, figures of embryos of fish, pig, man, etc. On 

 p. 147 we note the peculiar statement that the gill-slits are supported 



