PROGRESS OF MICROSCOPICAL SCIENCE. 
145 
The proposition to be established then is, that the young or em- 
bryonic state of the higher orders of plants resembles the full-grown 
plants of the lower orders. The writer finds his first proof in a com- 
parison of the fovillse of a pollen grain with full-grown Desmidiae. 
The points of resemblance are these : both are minute ; each consists 
of a single cell ; and both have an apparently aimless motion. Surely, 
these resemblances are not numerous or striking enough to found a 
law upon ; and if they were, they have not the remotest bearing upon 
the supposed law. Admitting that the fovillte “ may be regarded as 
one of the first steps towards the reproduction of plants of the highest 
type,” yet they are not in any sense a young or embryonic form of a 
plant. The fovillae constitute the male element, and are homologous, 
not to the embryo, but to the spermatozoa of animals. The supposed 
analogy between a Protococcus and a pollen grain is open to the same 
criticism. Nor is the correspondence between a full-grown Botrydium 
and a pollen tube of greater value. A pollen tube cannot, in any legi- 
timate sense, be called embryonic. The superficial resemblance of 
a mould fungus to a stamen is obvious enough ; but in reality no 
analogy can exist between them. The spores of the mould are em- 
bryos, and will develop, under favourable circumstances, into mould 
again. But pollen grains are not embryos, and never, under any cir- 
cumstances, grow into what, by any stretch of terms, can be called a 
new plant. Neither stamens nor pollen constitute a part of the embryo ; 
and no analogy drawn from them can have any bearing upon the laws 
of embryonic development. If such a law as the writer claims really 
exist, it must be found by studying the development of the ovule, the 
true homologue of the animal embryo. In view of such facts, all 
“ similar analogies ” and all similar “ proofs of the unity of design of 
the Creator ” may be easily dispensed with. 
The article proposes to extend the domain of a certain supposed 
law of the animal kingdom, so as to include the vegetable kingdom 
also. It has been shown, first, that no such law exists in the animal 
kingdom ; second, that not a single fact cited as proving it to be a law 
of the vegetable kingdom has the remotest bearing upon the question. 
If such hasty conclusions as these, wildly jumped at from no data, are 
to be allowed under the name of Science, her students will richly de- 
serve all the ridicule and sarcasm which a certain class are so fond of 
pouring upon them. 
The Structure of Connective Tissue. — Dr. G. Thin has read a paper 
on this subject before the Royal Society, of which the following is an 
abstract: * Transparent animal tissues, when sealed up fresh in aqueous 
humour or blood-serum, by running Brunswick black round the edge 
of the cover-glass, undergo a series of slow changes, by which, 
generally within a period of two to five days, anatomical elements 
mostly otherwise invisible become distinct. The paper is chiefly a 
record of observations made by this method. The author shows : 
1. After a horizontal section of the cornea has been sealed up for 
about twenty-four hours, the stellate branched cells are seen to 
* ‘ Proceedings of the Royal Society,’ No. 158. 
