122 HALF-AN-HOUR AT THE MICR0SC(3PE. 



to see the arrangement of the spores in their cases is to crush one 

 or two of the capsules on a sHde when about ripe ; they may be 

 easily and well preserved in glycerine. It may not be without 

 interest to remark that the usual number of spores in each ascus 

 with Erisiphei appears to be 2, with Bulgaria as seen here, 4 ; 

 but with the Ascomycetes in general 8, or a multiple of it, is the 

 usual number. 



Aleurone seems to me to be a mysterious and somewhat 

 questionable thing, which (although it will not do to finally dismiss 

 it in this way) still really " seems to be one of those things no 

 fellow can understand as yet." Nice work for the winter, when nuts 

 of various kinds may be readily procured, to enquire into it. A 

 description of Aleurone will be found in the Microscopic Diction- 

 ary, 3rd Ed. See also p. 125. 



Sonneratia section (see also p. 127). — All roots have more or 

 less of the structure here shown : large porous ducts, with me- 

 dullary rays, also sometimes pitted. One of those beautiful re- 

 condite marks of distinction which arrest the thoughtful student 

 now and again, has not been attended to in making this section. 

 This is the presence or absence of branched liber-cells, which 

 might serve for a criterion as to whether its right botanical place 

 were among the Mangroves or the Myrtles. 



Fibres of Keratose Sponge (PI. XIII., Fig. 3). — With regard 

 to this slide I differ decidedly from our vivacious friend (p. 125). 



This object is exceedingly interesting. When we remember 

 the near relationship of the Sponge Animals (flagellated Infusoria) 

 to the A??iosbcE, their power, though seemingly so structureless and 

 helpless, of building up complicated scaffolding, — look at the 

 wonderful way in which the beams (we might say) interlace and 

 occasionally become fused, like so many drawn-out strings of viscid 

 material become hardened as soon almost as formed, — we may 

 well feel delight as we gaze. The structure is so peculiar that it 

 deserves permanent record, and though incapable at present of 

 giving the name, I feel, for my own part, little doubt that both 

 species and genus may be revealed from the fragment. 



Dark-field Illumination. — I believe the credit of the simple 

 mode of dark-field illumination alluded to by one of our members, 

 belongs to our valued friend, Col. Horsley. As it is desirable our 

 members should know the plan, and it may be some time ere this 

 request reaches him, he will, for their sakes (I trust), pardon my 

 saying in his name that it is " done by taking the light in a plane 

 with the object, and dispensing with the glass reflector and the 

 condenser, so that the only reflected light is derived from the 



