350 THE AMERICAN NATURALIST [Vol. LV 



regions, as well as the Adriatic, it is probably common 

 along many American coasts where as yet overlooked. 



In seeking to refer the different forms of the bottle 

 animalcule found thus far in American waters to known 

 or new species we are confronted with ignorance of the 

 anatomy and the life history of the animals and thrown 

 back chiefly upon the secreted bottle or case, since it is 

 this alone that is commonly preserved, and since this also 

 presents preserved characters of form and proportions. 



In the life history as known there has been no restric- 

 tion of the possibilities of form and size change possible 

 to a single individual. We know that there are free- 

 swimming forms as seen by Claparede and more fully 

 studied by Wright and confirmed by Andrews and by 

 Penard. 



In some cases these swarmers arise from fission of the 

 parent as Mobius found to be true, but in many instances 

 the free-swimmers that swarm out are only the old forms 

 transformed into simpler larval shapes that have later 

 to make new bottles and then become again complex in 

 structure. In the former case the result of fission is one 

 free-swimmer of small size and one remnant individual 

 left to complete its perfect organization in the old bottle. 

 There are thus large and half-sized forms : both perfect 

 sedentary individuals and imperfect swimming larvae. 

 Moreover, we find that not only may each individual 

 greatly change its shape from muscular contraction, but 

 may change both shape and bulk under conditions other 

 than the optimum of good feeding environments. Noth- 

 ing is known of any conjugation and any influence this 

 may have upon form and size. 



While it is easy to assume that all the known forms of 

 bottles may prove to be the products of but one and the 

 same species widespread all through the various oceans 

 of the world, evidence for this is lacking, and not having 

 sufficient anatomical basis for classification, we must as 

 a practical expedient adopt the plan of Carl Dons and 

 determine the species by the form and size of the hot- 



