148 



THE AMERICAN MONTHLY 



[August, 



verrucosa. 



y. Sinuses inwardly more or less acute {z) . 



z. Base of semi-cell with a row of circular inflations 



z. •' " without inflations (aa) . 



aa. Lobules long, the lobes being deeply incised .... Torreyi., loS. 

 aa. '' short, the lobes not deeply incised {bb) . 



bb. Margins with spinous teeth . . . Ji?)ibriata, io<^\ papillif era., loc). 

 bb. " without spinous teeth (cc) . 



cc. End lobe somewhat remote from the lateral .... Ji/ubriata. 109. 

 cc. " approximate (dd). 



dd. Its apices not dentate nor divided, end convex . Psezidotorreyi^ loS. 

 dd. " " " end concave or emarginate, 



denticulata., 109. 

 dd. Its apices with denticulate appendages Novce Scotice.* 



Bulletin Torrey botanical Club, Dec, 1885. t Journ R. Micr. Soc, Dec, 18 



\_To be continued.^ 



On Mounting Certain Diatoms. 



A collection of diatoms recently 

 received from Mr. L. M. King, of 

 California, specimens of which he 

 offers for exchange, calls to mind 

 some methods of mounting such di- 

 atoms. The collection ^vas a re- 

 markably pure gathering of Isthmia 

 nervosa attached to seaweed. These 

 beautiful diatoms are very attractive 

 objectshoweverthey may be mounted, 

 but by the exercise of some skill and 

 patience their natural beauty may be 

 brought out far better than it is often 

 seen. 



There is a fine art in mounting 

 microscopic objects, that many of the 

 more stolid investigators affect to de- 

 spise ; but so long as the specimens are 

 not distorted, misshapen, or crushed 

 out of their natural condition, they lose 

 nothing for purposes of stud3% by be- 

 ing skilfullv prepared for exhibition, 

 and there is no doubt the inore per- 

 fectly the minute perfections of mi- 

 croscopic shell carapaces, and other 

 organic structures are revealed by our 

 art, the more attractive does our sci- 

 ence become. One may be very wise 

 and familiar with details of micro- 

 scopic structure through long studies 

 from the strictly scientific side, and 

 yet oblivious to the beauty and won- 

 der which would inspire another not 

 less learned. The difference is surely 

 in favor of those who most keenly 



appreciate the esthetic in their work, 

 for from that arises an inspiration 

 which elevates and broadens our 

 thovight, and is an incentive to fur- 

 ther study and search for the sources 

 and relations, not only of the organ- 

 isms themselves, but also of their 

 microscopic carvings and elaborate 

 ornamentation. Have we any reason 

 to suppose that the markings on a 

 shell of a diatom are merely for 

 beauty — to please the eye and arouse 

 the wonder of the microscopist.'^ Be 

 assured there is a deeper reason for 

 them, perhaps purely utilitarian, if 

 only to combine strength with light- 

 ness ; perhaps they are manifestation 

 of that tendency observed through- 

 out organic nature which some one 

 has characterized as ' a kind of or- 

 ganic crystallization ' — an expres- 

 sion that implies symmetry and 

 beauty of form, while it does not 

 conceal the want of knowledge that 

 underlies it. 



The usual method of mounting 

 Isthmia is by drying the frustules, 

 either on the seaweed or, freed by 

 shaking, on an opaque ground. In 

 this way, exercising some care in 

 selecting the most showy groups, very 

 attractive specimens can be obtained. 

 A dry mount of the free frustules can 

 be greatly improved by previously 

 clearing them, or rather removing the 

 dried endochrome. The best wav to 



