INFUSORIES. 43 
Paramecium chrysalis, Colpoda cucullus: the last appears to occur 
everywhere (Cosmopolite). HHRENBERG found Monas termo both 
in stagnant water at the Red Sea, and in spring-water on Mount 
Sinat. Colpoda cucullus is one of the most constant animals in 
artificial Infusions, and was formerly observed by LEEUWENHOECK 
in Infusions of pepper. 
APPENDIX 
TO THE CLASS OF INFUSORIES. 
ON (THE SO-CALLED) SEMINAL ANIMALCULES. 
( Spermatozoa.) 
Von Baer first (1827) introduced the name Spermatozoa (Nov. 
Act. Acad. Ces. Leop. Car. Vol. x11): earlier names, as animalia 
spermatica, Cercaria seminis, &c. have merely an historical value. 
The bodies, for the most part filiform, which have been observed 
in the fecundating fluid of animals of almost every class, have as 
microscopic creatures been ranked with Infusories: other writers 
class them with the Hntozoa, a proceeding which can only be justi- 
fied in a degree by the locality where they occur; while, on the 
other hand, it has introduced several wrong views. An independ- 
ent organisation, in virtue of which they might be considered as 
real animals, has not been discovered. ‘The cause of their motion 
is altogether enigmatical. 
LEEUWENHOECK, the discoverer of the Infusories, was the first 
also who made observations upon these small corpuscles that in 
appearance perform voluntary motion in male spermatic fluid. 
Their discovery is due to a medical student, named Ham, who an- 
nounced them to LeEuwENHOECK in August, 1677 (Phil. Trans. 
1678, No. 142; comp. Letter 113 in the Sevende Verfolg der Brie- 
ven, 1702, p. 65..., or in the Latin edition, Continuatio Arcanorum 
Nature, Operum Tomo u1. p. 60 sqq.). LeEvWENHOECK named 
these bodies animals, and observed them consecutively in different 
