li'^ TllK AMKUICAN MONTHLY [June. 



the prism case put in its place, the ocular bein": inscvtcd in the 

 short tuhe provideil for its reception. The ocular should point 

 downward. The lamp or other source of liijht should then he 

 disposed in such a way that it properly illuminates the object to 

 be examined, it beinjr expressly understood that no li'jjht shall 

 escape toward the observer excep.t that which first reaches the 

 object. A Beck lamp is conveniently adapted to this purpose. 

 If a piece of drawincj-paper is placed beneath the ocular, and the 

 room darkened, a brilliant imajje will be j^rojected on the paper, 

 and its reproduction can be easily accomplished with a maximum 

 of rapidity and a minimum of discomfit t. In i^uidinf^ the pencil 

 the drausjhtsman uses both eyes, and his spectacles if needed, 

 and sits in whate\er position he finds nK>>-t comf('Vtal)le. With a 

 proper lamp, antl carehd utilization of its lijjht. this device jjives 

 excellent resu'ts, with amplification up t<i four or five hundred 

 diameters. If a sensitive photojjraphic plate be substituted for the 

 drawing-paper, an exposiu'e of a few seconds will impress an 

 imai^e that may be developed in the usual way. — JVew I'ork 

 Mctlical Journal . 



Spiral Vessels of Castor-Oil Plant. 



From Note-book L of the American Postal Microscopical Club. 

 By R. H. ward, M. D., 



TROV, N. V. 



For the study of this specimen use only powers of 2 in. to 

 4-ioths in., or for the special jiurpose mentioned hereafter a low- 

 ano^led i -5th or i -6th ; as the contour of the spirals shows best with 

 objectives of greatest available depth of field, and higher jiowers 

 are unnecessary. Most satisfactory stereoscopic views can be got 

 with the Wenham binocular and a 1-2 to 4-ioths objective, with 

 special illuminating arrangement for working the binocular at its 

 best with mediinn or higher powers — by means of a horizontal- 

 slit diaphragm combined with a substage condenser, as introduced 

 by the writer at the Am. Ass'n for the Adv. of Sci. in 1S70 (see 

 Am. Nat.^ 1S70, pp. 635-8) and used with satisfaction ever 

 since that time. * * • 



This specimen, by the remarkable compactness of its spirals, 

 suggests its probable origin near the outside of an already formed 

 portion of the plant, as those which are formed in the bimdles 

 around the pith of a rapidiv growing shoot commonly have the 

 convolutions spread into an open spiral by the elongation mean- 

 while occurring in the tissues. This plant {Ricinus cottununis) 

 has long ago been noticed as furnishing " very striking examples " 

 (.Sachs) of these spirals in the stalk {rachis) of its flowers. 



The slide presents a field for a little practice in microscopical 

 mechanics of the easier sort. The cylinders of coiled fibres 

 whicii line the ducts are formed, in various plants, of single fibres 



