242 T. W. Engelmann on the Infusoria. 



nessed in only one other animalcule, viz. in Vorticella convallaria. 

 Claparede records the fact in V. microstoma. 



Engelmann confirms John Miiller's discovery of spermatozoa 

 in Paramecium aurelia, the nucleus being more or less enlarged 

 and filled with them. When pressed out, they exhibit no in- 

 dependent power of motion. They are not, as usually repre- 

 sented, thin rods equally pointed at both extremities, but have a 

 more bulky anterior and a thinner posterior extremity of greater 

 transparency. Their maximum length is O008 of a millimetre. 

 Among specimens of conjugated Paramecia, some, evidently only 

 recently united, possessed a nucleus of the usual oval form ; in 

 others it was more or less spherical, and presented constrictions 

 at different portions of its surface ; whilst in others, again, it 

 consisted of a coil of longer or shorter band-like segments. 

 Among such examples of conjugated forms, he also met with 

 single beings which contained, instead of a nucleus, from two to 

 four larger oval or round bodies, and a number of similar but 

 smaller ones. What had become of the nucleolus in these beings, 

 Engelmann was unable to surmise, nor could he, notwith- 

 standing his best efforts, discover the large seminal capsules 

 recently described by Balbiani. Lastly, individuals were met 

 with having embryonic globules, mostly lying in the posterior 

 half of the animals ; and frequently acinetiform embryos were 

 seen to detach themselves from these globules and make their 

 way to the surface through a special wide canal in the parent 

 animalcule. 



Engelmann observed conjugation, besides, in Paramecium 

 ambiguum, a new species, found in the lake at Eisleben, having 

 the figure of P. Bursaria, but colourless like P. aurelia, and 

 having a longer bundle of cilia at the posterior extremity. 



Instances of conjugation were also encountered in Paramecium 

 Colpoda (Colpidium, Stein), in several species of Trichoda, Cycli- 

 dium glaucoma, Cinetochilum margaritaceum, Coleps hirtus, in a 

 small Prorodon, in Nassula aurea, Lacrymaria elegans (new spe- 

 cies), and in Amphileptus fasciola. With the exception of the 

 conjugated individuals of the species last named, the union took 

 place at the fore part of the body; so that where the mouth oc- 

 cupied that position, as in Coleps, Prorodon, and Lacrymaria, the 

 oral apertures were in apposition. 



In the case of Amphileptus, the animals were united through- 

 out their length, with the exception of the distal ends of their 

 long necks and the contracted posterior extremities. No more 

 advanced phases of development were met with among the con- 

 jugated individuals ; but, in company with those of Amphileptus 

 fasciola, unusually broad specimens were encountered at times, 

 which possessed four nuclear bodies instead of the usual two 



