ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 729 



collecting,* whicli we regret not to be able to print in extenso. He 

 deals with " where to go," outfit, bints on shore collecting and climb- 

 ing, the best collecting places, and the period for work, preparing 

 hydrozoa and polyzoa with extended tentacles with osmic acid ; also 

 notes on getting insects, acari, &c., in the best condition to mount, 

 and on mounting insects, &c., in balsam. 



Collecting and Preparing Infusoria.f — Dr. H. Fol, in a fourth 

 contribution to the knowledge of the family Tintinnodea, says that 

 in the natural sciences method plays a principal part, but it is no- 

 where of greater importance than in microscopical researches : here 

 the fitness of the investigator consists much less in any particular 

 perspicuity than in the art of bringing into view the points that he 

 wishes to know. Hence, the employment of a new method has enabled 

 him to see clearly many things which he had previously been unable 

 to see, or which he had seen imperfectly and misunderstood. 



The collection of the Tintinnodea in the sea is an easy matter. 

 There is no danger of damaging them at the moment of their capture, 

 seeing that their test, into which they withdraw at the smallest sign of 

 danger, sufficiently protects them. They are pretty robust and swim 

 briskly about in the bottles several hours after their capture, and at a 

 time when many delicate animals are already dead or disfigured. It is 

 not, however, at the surface of the sea or under a bright sun that we 

 find them in the greatest abundance. In cloudy weather they rise to 

 the surface more readily than in bright weather ; and in the daytime 

 they are found chiefly at a depth of several fathoms. 



For their capture he employed a net of fine muslin of a conical 

 form attached to a ring about 50 cm. in diameter. The bottom of the 

 net presents a contracted opening like that of a " weel," which opens at 

 the middle of a much smaller net made of silken sieve-cloth with very 

 fine meshes. This latter is attached to a ring equilibrated by a frag- 

 ment of cork. This net of silken gauze does not injure the animals 

 at all, and it captures at least twice as many as the glass bottle which 

 some naturalists substitute for it. It is easy to understand in fact, 

 that the impermeable walls of the bottle compel the water to turn in 

 its interior, and cause eddies which carry out a considerable propor- 

 tion of the captured animals. 



With creatures so active and so difficult to observe alive under a 

 high power, it is of great importance to have a process which enables 

 them to be fixed instantaneously in their natural attitude before they 

 have had time to withdraw into their test, and which preserves 

 faithfully the details of their structure. 



Dr. Fol tried the various reagents most in vogue without attaining 

 his purpose. With weak osmic acid, he did not succeed in preserving 

 the cilia of the peristome ; and with a stronger dose the body became 

 absolutely opaque : in both cases there was always a strong contraction. 



* Journ. Quek. Micr. Club, i. (1883) pp. 233-43. 



t Arch. Sci. Phys. et Nat., ix. (1883) p. 554. Ann. and Mag, Nat. Hist., 

 xii. (1883) pp. 13-88 (1 pi.). 



