654 ^^^ POPULAR SCIENCE MONTHLY. 



chcete were unknown, they would undoubtedly be classed among 

 "monads" with the same right as Ileteromita ; why, then, may not 

 Ileteromita be a plant, even though the cycle of forms through which 

 it passes shows no terms quite so complex as those which occur in 

 Peronospora and Coleochmte f And, in fact, there are some gi-een 

 organisms, in every respect characteristically plants, such as Chlamy- 

 domonas, and the common Volvox^ or so-called " Globe animalcule," 

 which run through a cycle of forms of just the same simple character 

 as those of Ileteromita. 



The name of Chlamydoinonas is applied to certain microscopic 

 green bodies, each of which consists of a protoplasmic central sub- 

 stance invested by a structureless sac. The latter contains cellulose, 

 as in ordinary plants ; and the chlorophyl which gives the green 

 color enables the Chlamydomonas to decompose carbonic acid and fix 

 carbon, as they do. Two long cilia protrude through the cell-wall, 

 and effect the rapid locomotion of this " monad," which, in all respects 

 except its mobility, is characteristically a plant. 



Under ordinary circumstances the Chlamydomonas multiplies by 

 simple fission, each splitting into two or into four parts, which sepa- 

 rate and become independent organisms. Sometimes, however, the 

 Chlamydonnonas divides into eight parts, each of which is provided 

 with four instead of two cilia. These " zoospores " conjugate in 

 pairs, and give rise to quiescent bodies, which multiply by division, 

 and eventually pass into the active state. 



Thus, so far as outward form and the general character of the cycle 

 of modifications through which the organism passes in the course of 

 its life are concerned, the resemblance between Chlamydomonas and 

 Ileteromita is of the closest description. And on the face of the 

 matter there is no ground for refusing to admit that Ileteromita may 

 be related to Chlam,ydom.onas^ as the colorless fungus is to the green 

 alga. Volvox may be compared to a hollow sphere, the wall of which 

 is made up of coherent Clilamydomonads ; and which progresses with 

 a rotating motion effected by the paddling of the multitudinous pairs 

 of cilia which project from its surface. Each yb^voic-monad has a 

 contractile vacuole like that of Ileteromita lens / and, moreover, pos- 

 sesses a red pigment-spot like the simplest form of eye known among 

 animals. 



The methods of fissive multiplication and of conjugation observed 

 in the monads of this locomotive globe are essentially similar to those 

 observed in Chlamydomonas ; and, though a hard battle has been 

 fought over it, Volvox is now finally surrendered to the botanists. 



Thus there is really no reason v^'laj Ileteromita may not be a plant; 

 and this conclusion would be very satisfactory, if it were not equally 

 easy to show that there is really no reason why it should not be an 

 animal. 



For there ai-e numerous organisms presenting the closest resem- 



