OF THE PKOTOZOA. CILIATA. 365 



Podoplirya developing embryos, could not agree with the conclusion the latter 

 arrived at (viz. that they became VorticeUce), but was more disposed to believe 

 that they relapsed into Acinet<x. Ehrenborg (Ueber die FormbestdndigJceit 

 mid den Enhvicltehmgshreis der organisclien Formen, Berlin, 1852, at pp. 23, 

 24, and 34) attributes the theory to erroneous and hasty observation. The 

 supposed embryo of Acineta is, to his apprehension, simply a Tricliodina 

 which has been swallowed. To these strictures Stein replies that the Acineta - 

 bodies have no mouth, that they never contain any foreign matters taken as 

 food, and that no more than one Tricliodina appears in them at a time, al- 

 though many may live around them, and several would, no doubt, if taken 

 as food, be often found together in the interior. It is, moreover, to be noted, 

 that Acineta collected from the most different locahties contained the self- 

 same Trichodi na -torm, and that such forms occurred in sparing number. 

 Again, it must not be forgotten that the embryo may be watched in active 

 movement within the Acineta for the space of an hour, whereas Infusoria swal- 

 lowed by other animalcules are speedily reduced to a state of rest and de- 

 stroyed. Lachmann rejects the hj^oothesis, and gives, in much detail, his 

 reasons for so doing. At the same time he confirms the fact of " the forma- 

 tion of embiyos, not only in many Acinetina, but also in numerous other In- 

 fusoria " (A. N. H. 1857, xix. p. 232), and attests the fact of the nucleus 

 being primarily concerned in this act of development, adding some particulars 

 which require to be recorded. '^ The nucleus," he writes (loc. cit.), " is 

 usually seen, first of all, to divide into two or more parts, when the same 

 processes take place in one or several of these parts, which in other cases 

 occur in the undivided nucleus. Upon or in the wall of the nucleus, or of 

 one of its products of division, we now sometimes perceive small round glo- 

 bules, which increase in size, finally acquire a contractile vesicle, and become 

 converted into embryos ; these at last become furnished with cilia, escape out 

 of the parent animal, and swim about freely, generally in a form more or less 

 differing from that of the mother. Very clifi'erent numbers of embryos may 

 be formed in one section of the nucleus ; in the same species we sometimes 

 find many, and sometimes only one embryo formed in it ; and an embryo 

 which has been developed alone in a fragment of the nucleus is usually as 

 large as all the embryos formed in a similar fragment which has developed 

 many of them taken together. 



" The true import of the nucleus, of coiu^se, is not decided by this state- 

 ment ; [we cannot say] whether it is to be regarded as a germ-stock, in 

 which germs are formed asexually, as an ovaiy, in which the ova are de- 

 veloped at the same time, or, in accordance with Focke's views, as a uterus, 

 in which the ova or germs formed in another place (perhaps in the nucle- 

 olus ?) are further developed. 



" The fate of the embryos which are unlike their parents after their birth 

 is stiU unknown in most cases." 



Perty displays distinct opposition to Stein's views, but has not thoroughly 

 examined them, contenting liimself with an occasional critique in passing. 

 For instance, he states that those miniature beings regarded as the brood of 

 Vorticella, both by Stein and Ehrenberg (see p. 357), are in his opinion no more 

 than specimens of Cercomonas truncata (Duj.). Again, he remarks, Epistylis 

 anastatica is very rare at Berne ; and the Tricliodina grandinella, which Stein 

 represents to be its embryo, is very common in every collection of water ; 

 also Vorticella microstoma is most abundantly distributed, but its supposed 

 metamorphie condition, viz. Podophrya, very uncommon. Respecting the 

 latter animalcule, and likewise Actinoplirys, he adds an observation of his 

 own, which convinced him of the reproduction of these animals by minute 



