TRANSACTIONS OF SECTION K. 943 



there are only two left. These last two may then fuse at once, so a8 to leave the 

 now maturing zygospore with a single nucleus, or they may remain apart. The 

 last stages of maturation are accompanied by the appearance of oil drops in the 

 cytoplasm, which fuse towards its centre into a single large drop, reducing the 

 protoplasmic contents of the spore to a peripheral envelope, with one or two 

 parietal nuclei, as the case may be. 



I can only interpret this formation as a case of true apogamy, and attribute 

 to the process a value corresponding with the sexual process of Basidiobohis, since 

 they both have tha same starting-point, the same intermediate stage of nuclear 

 division, and the same final nuclear fusion. 



8. On ihe Life History 0/ Acrospeira mirabilis {Berk, and Br.). 



By R. H. BiFFEN. 



Loose brown masses of the spores of this fungus are occasionally found in 

 Spanish chestnuts. These spores are developed from the apices of hyphae coiled 

 into a spiral of, at the most, two turns, which becomes septate into three cells ; 

 the cell next below the apical one swells and becomes thick-walled, thus forming 

 a chlamydospore. The coiled hypha may also develop into a spiral resembling 

 the ascogonium of Eurothim, which, after investment by branches arising from 

 its apex, breaks down into chlamydospores. In this way bodies very suggestive 

 of the spore-masses of some of the ustilaginese are formed. Endoconidia are found 

 in old cultures. Some evidence has also been obtained for the existence of an 

 ascigerous stage. 



TUESDAY, SEPTEMBER 11. 

 The following Papers were read : — 

 1. Embryonic Tissues. By Professor Marshall Ward, F.R.S. 



I would submit for discussion whether we could not improve our terminology 

 and teaching regarding the natiu-e and growth of the tissues termed embryonic. 

 As is well known, Sachs and those whom he has influenced term all the tissues 

 of the growing points, cambium, pericycle, &c , embryonic tissues; but I want to 

 point out that this term in its simple form should be reserved for the embryo alone. 

 Only while the embryo consists of a few cells can we regard these cells as 

 embryonic tissues in the sense that all are nearly alike; at a later stage the 

 tissues of the growing points of stem and root have been derived from this 

 embryonic tissue, and in any case differ normally from it in that instead of being 

 capable of developing all or any parts of the plant, they are more and more 

 restricted to the power of developing only shoots, leaves, &c., or only roots. Still 

 more limited is the power of the cambium : it is normally confined to developing 

 new xylem and phloem — not even new organs— and similarly vnih. other so-called 

 embryonic tissues of subsequent derivation. In view of such facts, and of other;j 

 which we can all supply, I would suggest that we restrict the i^xra. embryonic tissue, 

 or primary embryonic tissue, to that of the embryo only, before the desmogeu 

 strands are laid down, and speak of all other tissues as derived or secondary tissues. 

 Thus the derived tissues of the growing points — capable of initiating organs as well 

 as tissues — might be termed secondary embryonic tissue, and the cambium, &c., 

 restricted embryonic tissues. 



The fact that such tissues retain sufficient of their primary properties to 

 develop whole organs, shoots, roots, &c., under modified or abnormal conditions 

 does not invalidate the distinctions referred to, and further classification and sub- 

 divisions along these lines could be made to meet the nt'cessities of such cases as 

 desmoyen (capable of laying down proto-xylem, &c.) and cambimn (capable of 



