290 Plant Origins. [Sess. 



same ground, is striking. In the earlier one there is ' hardly 

 anything said about making permanent preparations, and very 

 few stains are mentioned ; a microtome is discarded, — " sec- 

 tions may be made quite well with the hand." In this year's 

 edition (1897) all that is changed. Many pages are devoted 

 to microtomes, the sharpening of razors, embedding in paraffin, 

 and so on ; while all through the book very full instructions 

 are given for the preparation of stains. The change in micro- 

 scopic technique in these thirteen years has been enormous. 

 Now we know that the course of development through which 

 a race has passed is repeated to a greater or less extent in the 

 life-history of the individual, and it would be well to follow 

 the same law of recapitulation in our individual microscopical 

 studies. We should begin to use our microscopes without 

 microtomes, with very few stains, and, if possible, with living 

 or fresh objects. The appearance of a living cell — that of 

 Spirogyra or Tradescantia, for instance — is quite different 

 from that of a dead cell, however carefully mounted. 



There are, to my mind, three ways of using the miscroscope 

 to advantage: (1) Examine the objects fresh, make the sec- 

 tions by the hand or by a freezing microtome, and use a few 

 simple stains. Follow, in fact, such a book as Bower's ' Prac- 

 tical Botany ' or Huxley and Martin's ' Practical Biology.' (2) 

 Make collections to illustrate a particular group, such as fresh- 

 water algae or microscopic fungi. Many of these may be 

 cultivated, and preserved permanently in fluid cells. (3) Use 

 the more elaborate process of fixing, hardening, embedding, 

 and so on, after becoming familiar with simpler methods. 



The Microscopical Section resolved to occupy itself this 

 winter with a class of plants which has much interest for the 

 physiologist — the seaweeds and their fresh-water representa- 

 tives. From the difficulty of getting specimens, we could not 

 go on very methodically ; still, we got examples in fairly good 

 condition of most orders of British algre. Of the brown algae 

 we had Fucuses and Laminarias, Cutleria, Dictyota, and Des- 

 marestia ; of the green, we studied a number in fertilisation 

 and in fruit, such as (Edogonium, Vaucheria, and Spirogyra. 

 We had Ulothrix, Bryopsis, and Codium. We observed the 

 intercellular strands of protoplasm in Volvox, and we ex- 

 amined some of those enormous unicellular algae, Valonia ; 



