1889.] MICKOSCOPICAL JOURNAL. 149 



of the organs chosen for the early studies make them especially 

 valuable and convenient for the beginner in histology. Our normal 

 vision unites so much acquired perception with tlie direct sensation that 

 we do not realize how much more we think than we really see. The 

 microscope requires the beginner to enter a realm where a new series 

 of acquired perceptions must be learned, and hence the value of as sim- 

 ple objects as possible at the outset. 



We have examined cells like the green gland, liver, and intestine 

 cells which were secretive in function ; the intestinal muscle, motor in 

 function ; have studied the ovary with the peculiar egg-cell, the eye 

 with the peculiarities of a sense organ. Muscle and nerve histology 

 are, however, virtually not entered upon bv the course. A svstematic 

 course ought to include them. The original plan included studies upon 

 material by means of teasing from fresh material, but these studies must 

 be deferred. In place of them we hope soon to present a new course 

 of systematic studies upon mammalian histologv. The studies will all 

 of them be as simple as possible, and within the grasp of elementary 

 workers. 



Explanation of the Plate in February Number. 



Fig. I. Longitudinal section of the entire eye and cu. Cuticle. 



stalk of a small cray-fish. G. c. Ganglion cell. 



Fig. 2. Ganglionic matter from optic ganglion. Gn. Optic nerve ganglion. 



Fig. 3. Polar nerve cells from the optic ganglion. h. Hypodermis. 



Fig. 4. Crystalline cone (from Fig. i). n. Nucleus of polar ganglion cell. 



Fig. 5. Ideal plan of end organ of optic nerve with n. f. Optic nerve fibres. 



accessories (from Patten). n. 1. Nucleolus of polar ganglion cell. 



Fig. 6. Actual section from end of optic nerve. nn. Naked (?) nucleus. 



References bj- letters, etc., as follows : o. Optic nerve. 



Ax. n. Axial nerve fibre of crystalline rod. Ped. Pedicle. \ 



Bac. Bacillus. Pig. Pigment cell. 



B. m. Basilar membrane. Ret. Retinula. 



c. c. Corneal cuticle. Sp. Narrowed spindle of cone, 



c. h. Corneal hypodermis. 1,2,3,4. Portions of Optic nerve ganglion. 

 Cr. c. Crystalline cone. 



Hints on Mounting Objects in Farrjint's Modinni. 



By C. M. VORCE, 



CLEVELAND, OHIO. 



Attention is being turned again to this old but too much neglected 

 medium, the preparation of which on all the published formuhe is at- 

 tended with much trouble and vexation. The chief difficultv is in fil- 

 tering the viscous mass, for, notwithstanding the caution alwavs given 

 against stirring the mass to mix it thoroughly, in my own experience 

 the bubbles formed in stirring have uniformly disappeared on long stand- 

 ing in a warm room. Air bubbles in the completed mount, however, 

 exhibit all the obstinacy with which thev have been credited when the 

 mass is prepared on the formula commonly given, viz : two parts each 

 by weight of gum acacia and distilled water, and one part of glvcerin. 

 The gum is dissolved in the water, the glycerin added, the mass fil- 

 tered and a little camphor added to prevent mould. This makes a quite 

 viscous mass which quickly dries around the edge of the cover, but 

 from which air bubbles cannot be driven out nor poked out if once 

 imprisoned under the cover. 



For such objects as are usuallv mounted in pure glvcerin a much 

 thinner preparation of Farrant's medium is very convenient, and is 

 made by simply increasing the proportion of glycerin to gum. iVn- 



