EXPLANATION OF PLATE L. (continued). 



FIG. 



24. Conjoint endoplasts of Amphileptus anas after treatment with acetic acid, their 

 substance being thus shown to be divided up into numerous polygonal frag- 

 ments, each with a minute central refringent corpuscle, x 600 (Biitschli). 



25-28. Endoplastules or nucleoli of Paramcecium putrinum ; 25 and 26, normal forms, 

 x 2000 + acetic acid ; 27 and 28, successive phases during the process of 

 subdivision or fission (Biitschli). 



29-31. Endoplastules of Carchesium polypinumj 29, living condition ; and 30, after 

 treatment with acetic acid, x 1500; 31, example elongated preparatory to 

 subdivision (Biitschli). 



32. Endoplast of Paramacium bursaria, during process of subdivision, the normal, 



single, laterally attached endoplastule having already separated into two, x 

 800 (Biitschli). 



33. Twin endoplasts of Stylonychia mytilus j aspect exhibited at the commencement 



of the fissive process, the endoplastules in the vicinity of each endoplast also 

 commencing to subdivide, x 600 (Biitschli). 



34. Twin endoplasts of Stylonchia mytilus in a more advanced stage of subdivision, 



the endoplasts having already separated into four, both these and the endo- 

 plasts presenting a striated aspect, X 500 (Biitschli). 



35-37. Variously branched endoplast of Ophrydendron belgicum; 35 and 36 derived 

 from proboscidiform, and 37 from a vermiform zooid, x 800 (Fraipont). 



38. Ramifying endoplast from an erect main trunk of Dendrosoma radians, as 



observed by the author, x 800. 



39. Endoplastic system of Loxophyllum meleagris, consisting of numerous irregu- 



larly ovate nodular endoplasts, united to each other by a delicate thread- 

 like funiculus, x 600, + acetic acid, iodine, and picrocarmine (Biitschli). 



40. Irregular nodular endoplast of Hemiophrya Thouleti, x 500 (Fraipont). 



41, 42. Moniliform endoplast of Stentor polymorphus j 41, the entire structure, x 200; 

 42, a fragment more highly magnified showing internal refringent corpuscles 

 and connecting funiculus (Stein). 



43. Anterior region of undulating band-like endoplast of Stentor Rceselii, from the 



extremity of which one germ-sphere or embryo, with a central endoplastule 

 (the future endoplast) and incipient contractile vesicle, has become already 

 constricted off, a second similar germ-sphere being in an advanced state of 

 development, x 500 (Claparede and Lachmann). 



44. Twin endoplasts of Stylonychia mytilus, normal aspect, showing a distinct 



investing membrane, connecting funiculus, and laterally attached endoplas- 

 tules, x 600 (Biitschli). 



45, 46. Single endoplastic elements, with attached endoplastules, of Stylonyc hia mytilus. 

 45, Showing distinct differentiation of the anterior and posterior moieties ; 

 46, exhibiting at one extremity the delicate investing membrane, x 400 

 (Stein). 



47. More abnormal elongated endoplast of Stylonychia mytilus showing distinct 



bounding membrane and three striated laterally located endoplastules, x 400 

 (Stein). 



48. Single endoplast, with striated laterally attached endoplastule, of Kerona poly- 



porum, x 300 (Stein). 



49. Single endoplast of Oxytricha sp., whose substance has divided up into numerous 



polygonal germs, x 600 (Biitschli). 



50. Single endoplast, with contained germ-spheres, of Urostyla grandis, x 600 



(Biitschli). 



51. Compound racemose endoplast of Plagiotoma lumbrici, x 400 (Stein). 



52. Branching endoplast of young zooid of Dendrosoma radians as observed by the 



author, x 800, + osmic acid and picrocarmine. 

 53, 54. Branching, convoluted endoplast of Acineta mystacina, x 600 (Fraipont). 



