Balbiani on the Reproduction of Infusoria. 467 



male capsule, containing a bundle of spermatozoa bent into 

 an arc; e the mouth; v the contractile vesicles. M. Balbiani 

 has not been able to ascertain whether the ducts of the two 

 organs unite in one cloaca, or have distinct orifices. In some 

 genera he has not even satisfied himself of the existence of a 

 genital orifice. The coupling lasts from twenty-four hours 

 to five or six days, according to the development of the or- 

 gans. When they exist only as a simple rounded granule, 

 which is their lowest condition, the longest time is required, and 

 it diminishes as their evolution is advanced. " This remark ap- 

 plies not only to species in which the ovary and testicle are de- 

 veloped simultaneously and attain the end of their transforma- 

 tions at the same time, but also to those in which the evolution 

 takes place in an unequal and successive manner. Constantly 

 the female organ precedes the male organ, in order both of 

 appearance and development, so that in some species (Stentors, 

 Spirostomes) the ovary contains a number of eggs almost fully 

 developed, while no vestige exists of the male elements.-" 



M. Balbiani describes the nucleus as always present, but 

 varying in appearance according to its development. In young 

 animalcules it is a colourless, transparent, minute roundish mass, 

 the contents of which appear granulated when acted upon by 

 acetic acid. " Among most infusoria, the male and female 

 organs disappear completely after each effort of propagation, 

 and are immediately replaced by other productions of the same 

 nature, which, commencing their existence in a rudimentary 

 form, rapidly pass through the phases of their evolution, and 

 re-establish a complete sexual apparatus in a short time. From 

 their first appearance the new organs are of larger dimensions 

 than in young individuals, and thus offer a greater resistance to 

 the action of re-asrents, and enable their structure to be better 

 appreciated. If we examine a Stylonichia, Oxytricha, Stentor, 

 or other animalcule possessing this property, immediately after 

 reproduction has taken place, we do not find the nucleus under 

 the characteristic form belonging to the species, but in its stead 

 we note a body which offers the greatest resemblance to the 

 nucleus which the same infusoria presents in a young stage/-' 

 In' some species, M. Balbiani tells us, that the "primitive 

 female ovule " enlarges, and reaches maturity without multi- 

 plying itself, except that it divides when spontaneous fission of 

 the animal occurs ; in most, kinds, however, the primitive egg 

 gives rise to a number of other eggs by transverse division. 

 He observes : " The number of eggs which enter into the com- 

 position of the same chain, is often considerable. I have often 

 counted from twenty-five to thirty in certain large Trachelians 

 {Ampliileptus cygnus, Loxophyllum meleagris), and from forty 

 to fifty in adult specimens of Spriostomum ambiguum, imme- 



