250 Dynamic Theory. 



and the single celled algae, protococcus, &c. , a limited number were in- 

 tercepted, but of the infusorial animalcules, or their spores, ova re- 

 mains, or products, he never found one, in the course of observations 

 reaching into the hundreds. The larger infusoria are -^ of an inch in 

 diameter, and their smallest spores |L_ of an inch. The fungus spores 

 run from ^^ to ^^ of an inch. Starch particles from the air run 

 from ^ of an inch down. It follows, therefore, that the infusorial 

 products were big enough to be seen when the others were. Of the 

 whole of the dust products filtered from the air, only from one-half to 

 one-third (of one) per cent, are of organic origin. 



FIG. 110- Development of Euglena from 

 cells of a Confervoid Alga. ( Dr. Gros.) 



a. Unaltered cells of the Alga. 



b. Aggregation of the cell contents, first 

 stage toward forming the individual. 



c. Individuals assuming form of Euglena. 



$. Several cells thrown together by the oh- 

 literation of the partitions. 



Within the walls of a cell of a confervoid Alga after being sometime in 

 water, Dr. Gros has seen the protoplasm gradually assume the form and 

 characteristics of the Euglena, which is a green plastic vesicle that gen- 

 erally moves about with the help of a long anterior flagellum or tail in 

 front. Astasia is another variety hardly distinguishable from Euglena. 

 They have chlorophyl in their interior, and like vegetable products do 

 not take visible food, animal in form but physiologically apparently 

 vegetable. Bastian also claims to have seen Euglenae formed in the 

 small cells composing the submerged leaves of the Potamogeton ( Pond 

 weed). Euglenae there formed were as mobile as Amoebae, moving 

 about within the cell walls. They were bright green, the whole of the 

 chlorophyl and protoplasm having been absorbed in the creation of a 

 Euglena. Observations of Prof. A. M. Edwards are to the same effect. 



Bastian states on the authority of M. Nicolet, that under proper con- 

 ditions the protoplasm of the confervoid Alga, Chara, after being placed 

 in pure water, gives birth to a multitude of living organisms which, 

 after a time, undergo further modification into various forms of infusoria, 

 passing in 15 or 20 days through various stages into Monads, Amoebae, 

 Keronae, Yorticellae, Actinophrys and Rotifers. M. Nicolet says : "A 

 vessel prepared on the 29th of April and containing a single cell of 

 Chara ( a single internode ) yielded on the 15th of May following, in 

 addition to an incalculable number of (smaller) infusoria, 137 specimens 

 of the common Rotifer, two-thirds of which had been produced by re- 

 production. " 



It was the opinion of Louis Agassiz that the ciliated infusoria as a 

 rule are to be regarded as elemental or larval forms of other animals, 

 " most of them " (he says) far from being perfect animals, are only 



