216 



The President moved a vote of thanks to Mr. Cooke for his highly interesting 

 paper, which was carried unanimously. He also said he should be glad to hear 

 from Mr. Cooke what were his own views upon the subject of the alternation of 

 generations to which he had so forcibly directed their attention. 



Mr. Cooke, in response to the President's request, said that there was no 

 doubt of the alternation of generations in some fungi — as, for instance, the 

 bunt, where all were passed in the same host. But he felt great difficulty in 

 accepting such conclusions as those of Professor Oersted, where the generations 

 were passed in different plants, until confirmed by other observers. If the 

 spores of JEcidiiivi Berberidis were taken from the Barberry and sown upon 

 young wheat plants, and all these plants became infected with corn mildew 

 (Puccinia graminis), to which wheat is but too prone, it certainly seemed pre- 

 mature to say that the spores of the JEcidium caused the Puccinia to be de- 

 veloped as a second generation ; whereas it is much more probable that the 

 germs of the mildew already lay dormant in the wheat, and, at most, the sowing 

 and growing of the jEcidium spores only stimulated the mildew to a more rapid 

 development. He certainly thought such a theory more probable, and quite as 

 sound as the other. 



Mr. W. T. Suffolk said that it would be remembered that some time ago 

 (January 22nd, 1869) he made some observations upon the delineation of 

 microscopic objects. An accidental visit to a stationer's shop had supplied him 

 with a material for this purpose, which he thought was likely to prove very 

 useful. He was generally too idle to trouble to turn the microscope down so as 

 to use the camera lucida, but was in the habit of using a ruled diaphragm, placed 

 in the eyepiece, and then drawing the object upon paper ruled in squares ; but 

 there was sometimes a little difficulty in ruling paper accurately, especially 

 when the squares were required to be small. At " Letts's," a short time ago, 

 however, he found that they kept in stock paper ruled in this way quite accu- 

 rately — and that there were thirteen sizes of it to be had, ranging from 1 inch 

 squares down to 13 squares to the inch, specimens of which he had brought with 

 him to the meeting. The advantages of this method of drawing were that it 

 did not necessitate the disturbance of any part of the apparatus, and it did not 

 fatigue the eye as the camera lucida did. 



Mr. James Smith inquired if there was any definite size assigned to these ruled 

 squares, so as to enable anyone to indicate the size of the objects themselves ? 



Mr. Suffolk, in reply, said that it was only necessary to measure the value of 

 a space with the micrometer, and the ruling would then become at once avail- 

 able for the purpose of measurement. 



The President proposed a vote of thanks to Mr. Suffolk for his communication. 



The Secretary called attention to a new lamp-stand, designed by Mr. Richards, 

 for mounting the President's small lamps. It consisted of a ring foot, with an 

 upright rod screwed into it, upon which the mounting of the lamp was made 

 to slide, a set screw securing it at any height required. He thought, however, 

 that it would have been much more useful had it been provided with a universal 

 joint, so as to enable the lamp to be inclined at any required angle. 



Dr. Matthews also introduced to the notice of members another form of 

 stand adapted for the same lamps, in which a universal movement was secured 

 by means of a ball and socket joint in the centre of the foot. A very useful 

 addition to the lamp was also exhibited, consisting of a tube, which could be 

 screwed in the place of the bull' s-eye condenser in front of the open space in 



