Simplest Forms of Life. 225 



slide is set up to dry. When all the water on it is evaporated, 

 the clip is removed, the slide placed on a turn table, and a ring 

 of glycerin-proof cement applied around the edge of the cover. 

 The following cement is the best that I have found for this 

 purpose: 



Cox's Gelatin, 3 ii. 



Acetic Acid, fi. 3 i. 



Gum Ammoniac, gr. x. 

 Dissolve in a water bath and filter through cotton while warm. 

 This cement remains fluid when cold, and dries quickly. 

 After the ring has become set, or stiff, the whole slide is im- 

 mersed for a minute or so in a lo-grain aqueous solution of 

 Bichromate of Potash, and is then allowed to dry exposed to 

 light. The action of light makes the bichromated gelatin per- 

 fectly insoluble, even in boiling water, and thoroughly prevents 

 any escape of glycerin. After the ring has become hard, rings 

 of other cements may be applied to suit the fancy of the pre- 

 parer. 



1608 Pine Street, 



Philadelphia, Pa, 



THE SIMPLEST FORMS OF LIFE. 



BY B. EYFERTH. 



{Translated from the German for this Journal, with additions.) 



{Continued.) 

 H. utriculatum, Roth. In stagnant water; appears seldom, but 

 at times in abundance. 

 [Each swarm-spore grows to only a single cell, forming one side of 

 the mesh ; it never increases by sub-division forming two or more cells. 

 The nets may grow to the length of 30 cm.] 



6. Gen. Scenedesmus, M. Cells elliptical, [often] with points 

 on the ends, in simple or parenchymous series. Common 

 in standing water and aquaria. [Cells polymorphous.] 

 \a. Cells armed.] 

 Sc. quadricauda, Breb. Cells 0.02, egg-shaped. Terminal cells 

 with straight or bent spines. 

 [2-4-8 joined in a single straight series or double alternating one, all 

 straight, the median unarmed or some of them with the apex furnished 

 with a curved spine. 



