INDUSTRIAL PROGRESS DURING THE YEAR 1874. cv 



kingdom, and the characteristic relations of their organiza- 

 tions. 



"Researches on the Life History of a Cercomonad" is the 

 title of a capital paper by Mr.W.Dallinger and Dr. Drysdale, 

 a lesson in biogonesis which can be commended. They show 

 that the new cercomonad, when mature, multiplies by fission 

 for a period extending from two to eight days. It then be- 

 comes amoeboid : two individuals coalesce, increase in size, 

 and become a distended cyst, which eventually bursts, dis- 

 charging incalculable hosts of immeasurably small sporules; 

 which slowly enlarge, acquire liagella, become active, and 

 rapidly attain the parent form. They prove also that the 

 granules can withstand a much higher temperature than the 

 mature forms. 



Professor Leidy, noticing the enemies of Difflugia, says : 

 "I have repeatedly observed an Amoeba with a sw T allowed 

 Arcella, but never with a Difflugia. Worms destroy many 

 of the latter; and I have frequently observed them within 

 the intestine of JVais, Pristi?ia, Chcetogaater, and JEsolosoma. 

 I was surprised to find that Stentor polyrnorphus was also 

 fond of Difflugia. On one occasion I accidentally fixed a 

 Stentor by pressing down the cover of an animalcule cage on 

 a Difflugia whicli it had swallowed. The Stentor contract- 

 ed, and suddenly elongated, and repeated these movements 

 until it had split three fourths of the length of its body 

 through, and had torn itself loose from the fastened Difflu- 

 gia; nor did the Stentor suffer from the laceration of its 

 body, for in the course of several hours each half became 

 separated as a distinct individual. 



The following experiments were made by Professor Leidy 

 on the Revivification of Rotifer vulgaris : Two glass slides, 

 containing, beneath cover glasses, each about a dozen living 

 rotifers, were placed on a window T -ledge, the thermometei 4 

 being at 80, and allowed to dry. The next morning, about 

 twelve hours after the drying, water was applied, and the 

 slides examined ; the dried rotifers imbibed the water, and 

 expanded ; and in the course of half an hour revived, and ex- 

 hibited their usual movements, though some remained mo- 

 tionless. The same slides were again dried, and examined 

 the next day ; only two, after moistening, were noticed mov- 

 ing on each slide. He next submitted a slide, upon which 



