72 BEITISH ASSOCIATION TOE 



be the embryo of a larger "worm in course of migration, I urged that a particular 

 investigation was needed for each particular species. 



Among the most bi-illiant of recent acquisitions to this part of Physiology, have 

 been the discoveries which have resulted from such special investigations. Kuchen- 

 meister and Von Siebold have been the chief labourers in this field. After noticing 

 some of the results of those labours, he said — Since the time when it was first 

 discovered that plants and animals could propagate in two ways, and that the 

 individual developed from the bud might produce a seed or egg, from which also 

 an individual might spring capable of again budding, — since this alternating mode 

 of generation was observed, as by Chamisso and Sars, in eases where the budding 

 individual differed much in form from the egg-laying one — the subject has been 

 systematised, generalized, with an attempt to explain its principle, and greatly 

 advanced, especially, and in a highly interesting manner, in Von Siebold's late 

 treatise, entitled ' Wahre Parthenogenesis bei Schmiterlingen und Bieuen,' in 

 which the virgin production of the male or drone bee is demonstrated. Von 

 Siebold having subjected to the closest microscopic scrutiny and experiment the 

 conclusion to which the practical Bee-master Dzierson had arrived relative to the 

 cause of queen-bees with crippled wings producing a swarm exclusively of drones 

 has demonstrated that the male bee is produced from an egg which has been sub- 

 jected to no influence save that of the maternal parent; whilst such egg, if im- 

 pregnated, would have produced a female or worker bee. The now well investi- 

 gated phenomena of parthenogenesis in Hydrozoa have resulted in showing, as 

 in the analogous case of Entozoa, that animals differing so much in form as to 

 have constituted two distinct orders or classes, are really but two terms of a 

 cycle of metagenetic transformations — the acalephan Medusa being the sexual 

 locomotive form of the agamic rooted budding polype, just as the cestoid tsenia is 

 of the cysted hydatid. In Hydrozoa (hydroid polypes or sertularians) the young 

 are propagated, as in plants, by "buds," and also, as in most plants, by "germs" 

 or " seeds": these latter are contained in "germ-sacs" projecting from the outer 

 surface, which is another analogy to the flowering parts of plants. The first 

 acquaintance with these marvels excited tiie hope that we were about to penetrate 

 the mystery of the origin of different species of animals ; but as far as observa- 

 tion has yet extended, the cycle of changes is definitely closed. And, since one 

 essential step in the series is the fertilized seed or egg, the Harveian axiom, 

 " omne vivum ab ovo" if metagenetic phases be ascribed to one individual, may 

 be still predicated of all organisms Avhieh bear the unmistakeable characters of 

 plants or of animals. The closest observations of the subjects of these two 

 kingdoms most favourable to clear insight into the nature of their beginning, 

 accumulate evidence in proof of the essential first step being due to the proto- 

 plasmic matter of a germ-cell and sperm-cell ; the former pre-existing in the form 

 of a nucleus or protoplast, the latter as a granulose fluid. In flowering plants 

 it is conveyed by the pollen-tube, in animals and many flowerless plants, by loco- 

 motive spermatozoids. The changes of form which the representative of a species 

 undergoes in successive agamically propagating individuals are termed the " meta- 

 genesis" of such species. The changes of form which the representative of a 

 species undergoes in a single individual, is called the " metamorphosis." But 



