56 



KNOWLEDGE 



[Majich 1, 1899. 



certain rather persistent contrasts. Thus, comparing the 

 periods of increase of spots with those of decrease, there 

 seems to be a tendency to more wet (more wet months) in 

 the latter. 



An instructive comparison, I think, is that of the five 

 years just after minima with the five years ending with 

 minima — i.e., (roughly) the period of growth of the spots 

 with the latter part of the period of decline. 



Consider this table : — 



Fire Years 



after 



Minima. 



• 1824-1828 

 1834-1838 

 1844-1848 

 1857-1861 

 1868-1872 

 1880-1884 

 1891-1895 



Five Years 



ending 

 Minima. 



1819-1823 

 3829-1833 

 1839-1843 

 1852-1856 

 1863-1867 

 1875-1879 

 1886-1890 



+ 19 



Thus one group apparently tends to be dry and the 

 other to be wet. The one exception (1886-18flO), with 

 preponderance of dry months in the second group, occurs, 

 we may remark, in one of Briickner's dry periods. 



Should this state of things appear to any merely 

 fortuitous, they might, perhaps, further see reason for an 

 adverse view in the fact that the relation indicated certainly 

 does not hold good everywhere. 



Are we not, however, beginning to see that sunspot 

 influence on weather, if probably real, is probably, also 

 complex in character, and that the rough generalizations, 

 hitherto considered applicable to it, may be found to need 

 revision ? 



THE MYCETOZOA, AND SOME QUESTIONS 

 WHICH THEY SUGGEST.-II. 



By the Right Hon. Sir Edwabd Fey, d.c.l.. 



and AftNEs Fry. 



LL.D., F.R.S. 



NUCLEI.— In the history of the theory of cells it was 

 early discovered that there is in each cell a smaller 

 structure called the nucleus, which was originally 

 supposed to be a vesicle in the cell, but has been 

 now ascertained to be a portion of a special 

 substance distinct from protoplasm. The nucleus has 

 been found to exercise something like a dominant 

 influence on the destiny of the cell—" all the formative 

 and nutritive processes seem to be dependent upon it," 

 and, moreover, it plays an important part in each process 

 of cell division — i.e., in some or all cases of the division 

 of the ceU the nucleus undergoes a like division. This 

 division occurs in three ways, of which two only need 

 now be noticed. One of these modes of division is very 

 simple. The nucleus gets constricted in the middle, the 

 connecting link grows sUghter and slighter, and breaks. 



and we have two nuclei where before we had one. 

 The other method by which nuclei divide is a highly 

 complicated and remarkable process, known often by the 

 long name of Karyokinesis — i.e., the movement of the 

 kernel. In this process certain polar bodies appear, round 

 which the constituents of the cell gather, and the nucleus 

 assumes a curious spindle-like shape before the division 

 actually occurs. 



Now, in the mysies, we have, as we know, no true cells 

 with cell walls, except, perhaps, in the spores themselves, 

 but we have protoplasts, in the form of swarm spores, pro- 

 ^'ided with nuclei, as shown in Fig. 3. In the Plasmodium, 

 too, we have nuclei, and it has been supposed that the 

 original number of nuclei in the Plasmodium corresponded 

 with the number of the constituent protoplasts, but it has 

 been shown that the nuclei increase vastly in number, and 

 that this division and multiplication of nuclei takes place 

 in all the stages of the swarm cells, of the Plasmodium and 

 of the sporangium. The question whether this multiplica- 

 tion of nuclei in the myxies at the various stages takes 

 place by simple division or by the complicated process of 

 Karyokinesis is one which has been carefully investigated, 

 although the results can hardly as yet be considered as 

 conclusive. They appear to be, first, that Karyokinesis 

 is the method pursued in the swarm spores when they 

 divide, and again at a later stage in the sporangium shortly 

 before the formation of spores: and, secondly, that the 

 multiplication of nuclei in the plasmodium is sometimes 

 accompUshed by Karyokinesis, but probably, also, by direct 

 division. 



Powers of Protoplasm. — What are the powers with 

 which the simple naked protoplasm of the Myxomycetes 

 is found to be endowed ? It is endowed with — 

 (a) The power of motion ; 



('0 

 (.0 



(9) 

 (0 



The power of seizing and digesting food ; 



A capacity for excreting what is not suited for 



retention by the organism ; 

 A capacity to perform chemical work ; 

 A capacity to assume and change colour ; 

 The power of attracting and being attracted by 

 and uniting with other protoplasm of the same 

 species ; 

 A converse power of avoiding the protoplasm of 



other species ; 

 A power to assume a definite external shape, and 



to divide mto spores and non-spores ; 

 A capacity to enter into a state of suspended 

 vitality. 



" Life never can arise out of or depend on organization," 

 wrote John Hunter; and unless naked protoplasm be 

 regarded as organized, his remark seems to be verified 

 and proved past dispute. 



Let us consider some of these faculties more in detail. 

 Motion. — The motions exhibited by the protoplasm of 

 myxies are of the most varied kind. We have already 

 mentioned the jumping motion of the swarm spores and 

 the crawling action of the plasmodium : now we will ask our 

 readers to turn again to Fig. 4, and to allow us to describe 

 what is seen in a crawling plasmodium under a microscope. 

 The Plasmodium is differentiated into two parts : the 

 larger and interior part contains minute oil granules, or 

 mierosotmita ■ the external layer is free from granules, and 

 is perfectly transparent like glass or water. The darker 

 and granular interior protoplasm is known as the endoplasm: 

 the hyaline superficial layer is known as the ectoplasm. 

 Fig. 4 is on too small a scale to exhibit this difference 

 distinctly. 



There are two motions here to be observed, though they 

 are not disconnected with one another : first, the pulsating 



