52 COLEOCH&TE. 



MINUTE STRUCTURE. 



I. VEGETATIVE CHARACTERS. 



Remove and mount some of the plants, and by use of the 

 low power observe: 



1. The form and arrangement of cells composing the plant. 



2. The number of cells in thickness. 



3. Whether the plant is a compact disk. 

 By using the high power examine: 



4. The details of cell-structure and arrangement. 



Outline an entire plant and draw in detail a sector of the 

 plant from the center of the disk to the margin. 



II. REPRODUCTIVE CHARACTERS. 



5. Observe cases where the disks may be dividing to form 

 new ones vegetatively. 



At the tips of branches at the edge of the disk the sex-organs 

 arise. Note the reproductive structures as follows: 



6. Oogonium, a somewhat elongated cell narrowed ab- 

 ruptly into a long tubular projection (trichogyne)\ ob- 

 serve the egg within the oogonium. 



7. The antheridia, small cells formed on the marginal 

 ends of filaments. Observe whether in those seen any 

 sperms are being formed. 1 



8. After the egg is fertilized the base of the oogonium becomes 

 encased, and after a period of rest the oospore rearranges 

 its contents to form a number of zoospores that escape 

 and grow into new Coleochate plants. Try to find some 

 of these stages. 2 



Make drawings illustrating reproductive structures of Coleo- 

 chate. 



1 If good prepared slides are available, they will be found advantageous 

 in the study of 6, 7, and 8. 



s For a good statement and illustration of the details of reproduction 

 in ColeochcKte see "Die Entwickelung der Sexualeorgane bei Coleochcete 

 pulvinaia," by E. Oltmanns. Flora, 85: 1-17, 1898. 



