94 ORGANIZATION OF THE INFUSORIA. 



various other species. As elicited by the recent investigations of Messrs. 

 Dallinger and Drysdale, it occasionally happens that the coalescence of three 

 or four or more metamorphosed or amcebiform Flagellate animalcules takes 

 the place of the more ordinary conjugation of two zooids only. In this 

 latter instance, as illustrated by the biflagellate type Heteroviita uncinata, a 

 close approximation is made towards that multiple coalescing process by 

 which out of a number of similarly metamorphosed or flagellate zooids 

 the compound amcebiform plasmodium of the Mycetozoa is built up ; a 

 modification of this phenomenon would also, as hereafter shown, appear to 

 accompany the construction of the compound locomotive gemmules, or 

 so-called " ciliated larvae " of the Spongida. 



While the interpretation of the sexual or genetic reproductive phenomena 

 of the Infusoria embodied in the earlier portion of this present section 

 adapts itself most nearly to the data elicited by the most recent investiga- 

 tors, among whom the names of Engelmann and Butschli are especially 

 noteworthy, it by no means represents the one regarded with the greatest 

 favour prior to the publication of the discoveries of these authorities, nor 

 even yet, perhaps, the one at the present day most extensively maintained. 

 From almost the earliest epoch of their history, the probable propagation of 

 infusorial animalcules by a sexual or genetic process analogous to that 

 which obtains among the higher animals has now and again been suggested. 

 Such an interpretation was thus, though inaccurately, attributed by Sir 

 Edmund King, in the year 1693, to the ordinary process of transverse fission 

 witnessed by him in a species of Euplotes, while O. F. Miiller, in his 

 ' Animalcula Infusoria,' 1786, figured and described that conjugative process 

 or genetic union of Paramecium aurelia since generally admitted, so far as 

 the external features are concerned, to be substantially correct. 



Passing over, for the present, that far-fetched and long since abandoned 

 hypothesis advanced by Ehrenberg, in which the contractile vesicle was 

 regarded as a spermatic reservoir engaged in the continued fecundation of 

 closely associated ova, the far more practicable and intelligent one origi- 

 nating with Balbiani in the year 1858 may be cited. By this accomplished 

 investigator it was at the foregoing date first pointed out that the hitherto 

 supposed instances of longitudinal fission, as figured and described by 

 Ehrenberg, of Paramecittm bursaria and other free-swimming Ciliata, had 

 nothing to do with such a duplicative process, but were indicative of a 

 genetic union or conjugation between two individual zooids. Balbiani 

 further maintained that the nucleus and nucleolus during such conjugative 

 process became transformed into veritable sexual organs, of which the 

 nucleus or endoplast, dividing up into a number of spheroidal fragments, 

 performed the function of an " ovary," and the nucleolus or endoplastule in 

 the same way, after first assuming a longitudinally striate aspect, and then 

 separating into a number of rod-like spermatic elements, fulfilled that of a 

 testis or "seminal capsule." During the process of conjugation, lasting in 

 this species, according to Balbiani, five or six days, the nucleoli or seminal 



