31b 



He then read a paper on " Circumnutation in Fungi," and invited observa- 

 tions on the subject. 



The President observed that Darwin had gone no lower than ferns in the 

 vegetable scale for evidence of circumnutation. In order to observe the 

 growth of the moulds which he had described it was only necessary 

 to sow some spores in a drop of water contained in a cell, the cover 

 being cemented down to keep in the moisture. On watching the cell 

 for five or six hours the spores will be found germinating and thrusting 

 the germinating thread through the water into the air. If the cell 

 is not too deep the whole process may generally be seen on the cover 

 glass. At first the germinating threads are thrust out straight, but after 

 being pushed out about five or six times the diameter of the spore, by 

 careful watching, the process of circumnutation may be seen to commence, 

 that is, a circular movement going on, and, as in the hop-plant, feeling round 

 in the air, as if seeking^ something to climb. The same movement takes 

 place in the mould, as in the hop-plant, all the while turning round an 

 imaginary axis ; and as it vegetates within the cell the growing point 

 continues to move round, circumnutating as it grows, at the same time 

 lengthening out, while the motion ceases in the hinder part, which seems to 

 be attached to the slide. The growing point alone keeps moving round, and 

 the whole thread maintains a corkscrew form, just as the stem of the hop- 

 plant coils round its supporting pole. He had some 30 to 40 slides, each con- 

 taining G or 8 plants, in which everyone of the branches had taken this 

 spiral form, and he hoped at some future gossip-night to bring up a few of 

 the slides to show to the Members. He thought it probable that the same 

 thing takes place in the growing point of many of the lower cryptogams. 

 It was remarkable that, in such a simple plant as the common blue mould, 

 there should be such an analogy to the hop. 



Mr. Badcock thought that the subject was very suggestive and important. 

 He enquired if the President could indicate the cause of the movement. He 

 had observed something of the kind in studying pond life, and he wished to 

 know the special object in view, and whether the tendency was not uni. 

 versal. 



The President replied that if the movement was not universal it was far 

 more common than was generally supposed. Movement in plants is as uni- 

 versal, though more limited, as movement in animals. Darwin has pointed 

 out that in almost every plant he has examined some part of it moved. The 

 plant being fixed by one point there is only one movement of which it is 

 capable. Most plants had some movement, either regular or irregular, 

 of this kind. As to the cause. He had no doubt there were several causes. 

 First the influence of light. Plants that turned towards or from the light 

 would circumnutate. Darwin divided circumnutation into three or four 

 forms. Besides typical circumnutation there were also — 1, an attrac- 

 tion towards the earth — Geotrojrism. 2, a turning towards the sun — 

 Heliotropism. 3, a turning from the sun — Aheliotropism. There is 

 no doubt that the hop-plant movement is one in search of something 

 to which to attach itself, that is the primary intention of the move- 



