88 THE AMERICAN MONTHLY [Mch 



zoa, which are very common in warm seas. Though brought 

 up abundantly by the tow-net when collecting- in such re- 

 gions, they are perhaps somewhat less familiar, at least to 

 inland microscopists, than those other, more highly devel- 

 oped and more showy radiolarian groups which are rough- 

 ly classified and highly admired as "Polycystina." It will 

 be noticed that these are composite forms,of which the nu- 

 merous globular zooidsareof the familiar radiolarian type, 

 but whose skeleton has not attained a greater dignity or 

 utility than that of a few slender, branching, silicious spic- 

 ules (suggestive, in general appearance, of some sponges) 

 that surround the individual zooids, and protect them more 

 or less, in lieu of the comparatively massive and elaborate 

 "silicious skeletone" of the nearly related Polycystina 

 groups. The form and arrangement of the delicate and 

 beautiful spicules is best seen with a stereoscopic binocu- 

 lar (as Wenham's) and a ^irds or low-angled 4-10ths obj. 

 The "punctate" appearance of the globules, which may 

 well have given rise to the specific name, is readily seen 

 with the same powers. If using a %th or l-5th, which is 

 seldom advisable, use only those of low angles and long 

 working focus, and use with very great care ; as the speci- 

 men is thick, and many a #th would destroy the mount be- 

 fore focusing through the object. — R. H. Ward. 



Midrib of Leaf of Strelitzia. — This section is from the 

 midrib portion of the leaf of a south Africa monocotyledo- 

 nous plant of the banana family. It is specially interest- 

 ing for the gigantic size, especially antero-posteriorly, of 

 some of its fibrovascular bundles ; also for the very large- 

 celled, frail, thin-walled and loosely-packed parenchyma, 

 which has been unable to fill,even with that poor tissue.all 

 the area of the section, but has left large air-spaces, be- 

 sides a liberal suply.of the ordinary ducts,and of giant size. 

 The vacant spaces occupy, from a quarter to a third of the 

 whole area. All these peculiarities are evidently due to the 

 rapid growth, especially in thickness,of this member ; such 

 exuberance of growth being well-known in the banana plant 

 and other members of the same family. There will be no- 

 ticed, also,the very highly differentiated and perfect though 



