478 Mr. J. B. Farmer. On the Relations of the [Dec. 14, 



tral connexions. Degeneration and sclerosis of the so-called " ascend- 

 ing root " was traced as far as the 2nd cervical nerve, after section of 

 the sensory division ; and atrophy of the so-called " descending root " 

 was observed after section of the motor division. 



We were unable to confirm the existence of a direct cerebellar root 

 to this nerve. 



IV. " On the Relations of the Nucleus to Spore-formation in 

 certain Liver-worts." By J. BRETLAND FARMER, M.A., 

 Royal College of Science, London. Communicated by 

 Professor VINES, F.R.S. Received November 9, 1893. 



It is well known that, as a general rule, during the formation of 

 spore tetrads from their mother cells, the nucleus of the latter com- 

 monly undergoes two successive bipartitions. Each of the resulting 

 four nuclei ultimately becomes a centre for the aggregation of a 

 portion of the original protoplasm, whilst division of the whole im- 

 mediately follows by means of cell walls. 



Though the above method is the one most commonly followed 

 during the process of spore development, so far as the essential 

 features are concerned, it is by no means the invariable one. Prob- 

 ably, however, it is to be regarded as typical, and the deviations 

 about to be described should be interpreted as modifications of it. 



Anyone who is familiar with Hofmeister's drawings, or who has 

 ever seen spore production actually going on in the Hepaticse, must 

 have noticed that, in many species, the mother cell of the tetrad 

 becomes four-lobed previously to its breaking up into its four spores. 

 This lobed appearance is seen whilst the original nucleus is still 

 resting, and is due to a bulging out of the cell wall in four directions, 

 accompanied by an ingrowth of cellulose into the lumen of the cell, 

 and towards the nucleus. 



If the process be followed in Aneura muUifida, the intruding walls 

 are seen to closely approach the nucleus while this body is still in the 

 resting state. The latter body then divides very rapidly, forming 

 first ten, then twenty, chromosomes, which are arrayed along a very 

 short spindle at the centre of the cell. Then another spindle appears 

 in a plane inclined to that of the first, and the number of the chromo- 

 somes is apparently about forty, though, by reason of their small 

 size and the difference in their planes, it is difficult to be quite certain 

 as to their number. The nucleus here then goes through the ordinary 

 form of karyokinesis, but in a somewhat compressed form. The four 

 groups of ten chromosomes then move off along the achromatic 

 spindles to their respective lobes, and the further ingrowth of the 

 cell walls to the centre, where they meet, cuts off the several proto- 



