No. 3-] THE PROTOZOA AND METAZOA. 715 



Ishikawa speaks of "radial-fibers" (section 12), but as these 

 are analogous in every way to similar fibers in ordinary mitosis, 

 I see no reason for adopting this term in preference to the cur- 

 rent name "mantle-fibers." 



The present paper deals almost exclusively with the points 

 touched upon by Ishikawa in sections 3-14, 16, and 17. The 

 details of chromosome-formation are found to differ consider- 

 ably from Ishikawa's account, and for the first time the forma- 

 tion of the nuclear plate in Noctiliica is described. Ishikawa's 

 observations in regard to the sphere and centrosome are, in the 

 main, confirmed. 



Before giving the results of my observations I wish to express 

 my obligation to Professor Wilson, not only for the material 

 upon which most of my work was done, but also for his kind 

 advice and unceasing interest. 



I. MATERIAL AND METHODS. 



The material for my work was collected partly by Professor Wilson at 

 Beaufort, N. C, in June, 1895, and partly by myself at Port Townsend, 

 Puget Sound, in July, 1896. In the latter place it was found in great abun- 

 dance, often covering hundreds of square yards, its presence indicated by 

 brilliant phosphorescence by night, or in daylight, when wind and tide were 

 favorable, by patches of brilliant orange.' They were collected early in the 

 morning and preserved at intervals during the day and succeeding night, and 

 all stages of vegetation, division, and spore-formation were thus secured. 

 Five different killing agents were used, viz., corrosive sublimate (saturated 

 in normal salt solution), sublimate-acetic (10 per cent acetic), picro-acetic 

 (Boveri's formula, with i per cent acetic for the Beaufort material, satu- 

 rated picric with 5 per cent acetic for that from Puget Sound), Hermann's 

 fluid, and Flemming's stronger solution. 



The material was prepared for study either by mounting in ioto or by 

 imbedding in paraffin and sectioning. Considerable difficulty was expe- 

 rienced in handling such small objects until the following method was 

 devised. The alcohol containing Noctihtca was poured into a glass cylin- 

 der two inches long and one-half an inch in diameter, covered at the lower 

 end with bolting cloth of such fineness that the Noctiluca were held back 

 while the alcohol passed through. They were then readily handled by car- 



1 Noctihtca was observed and collected in Alaskan waters as far north as Juneau 

 and Sitka, and even in Glacier Bay, where the water is at a constant low temper- 

 ature. The water of Puget Sound is deep and cold (about 51° at all depths), but 

 at Sitka it is shallow and perceptibly warmer. 



