fun: 19, 1884] 



NA TURE 



183 



organ is practically one whole — one mass of protoplasm cut 

 up into chambers which communicate with one another, and 

 bounded by a membrane on the exterior. If, on the oilier hand, 

 the communications between the protoplasm of neighbouring 

 cells are only established after a complete septum has been 

 formed, then it may or may not be that the above view holds, 

 —so far as the continuity of the protoplasm of mature cells is 

 concerned, it affords no conclusive proof against the very gene- 

 rally accepted idea that the plant consists of cell units aggregated 

 into colonies, tissues, &c. 



Turning for a moment to certain investigations which throw 

 light on this matter from totally different directions, it will be 

 seen that there is much to be said for the view lately stated by 

 Sachs, and first hinted at by Hofmeister, that a much closer 

 relation of cell to cell exists than can be well explained by the 

 theory that a plant is a sort of cell republic, consisting of aggre- 

 gated cell units. 



Strasburger's well-known investigations on the process of cell 

 division have led to the remarkable and startling result that the 

 septum or partition-wall, formed when a cell divides, is in 

 general a solid membrane built up by the aggregation of certain 

 particles (microsomes) which become arranged into a plate (the 

 cell-plate) at the equator of the dividing mass of protoplasm. 

 These microsomes are conducted to this equator, and there 

 mobilised by certain delicate fibrillse in the protoplasm ; these 

 fibrillae form the well-known spindle-like figure, and are con- 

 tinuous across the equator. If the microsomes travel along the 

 fibrillre from either side, and are fitted together between them, 

 it seems difficult to doubt that the continuity of the protoplasm 

 observed later simply depends upon the persistence of this 

 primitive continuity, and such appears to be the case. 



The proof that the primitively continuous fibrillar remain con- 

 tinuous throughout does not yet exist however ; and although 

 it is so likely, it cannot be forgotten that protoplasm possesses 

 a marvellous power of boring through and dissolving even adult 

 cell-walls, as is evident in the exit of zoospores or the entrance of 

 parasites through cell-walls, the formation of pollen-grains, &c. 



But we have not yet exhausted the evidence for the view that 

 the continuity of the protoplasm through the cell-walls of fully 

 developed organs exists from the first. 



The investigations of Strasburger, Schmitz, and others, on 

 the protoplasm and nucleus of vegetable cells, have yielded the 

 results that, in the first place, many cells believed to be devoid 

 of nuclei really possess these structures, and often in enormous 

 numbers ; and, secondly, that many cases of division occur where 

 a delicate cell-wall is formed in the equatorial plane between 

 the two dividing nuclei, but only to disappear later. In many 

 other cases no recognisable septum is formed at all. The inter- 

 nodes of Chara and the zoosporangia of Achlya may be cited as 

 examples. In Vauckeria, Caulerpa, &c, again, we have plants 

 each of which is practically a single cell with numerous nuclei : 

 these nuclei divide as the cell grows, but no cell-walls are formed 

 — the plant remains " unicellular." 



If in such cases a septum were formed each time a nucleus 

 divides, the protoplasm of the Vauckeria, Caulerpa, &c, would 

 become divided up into cells ; and if the septum in each division 

 were incomplete only in so far that it allowed the fibrillje of 

 protoplasm which carry and arrange the microsomes to remain 

 continuous through it, we should have essentially the condition 

 of things demonstrated by Hanstein, Tangl, and especially by 

 Gardiner. 



But it would in such a case be imperative to express the facts 

 in accordance with the primitive state of affairs — the protoplasm 

 of the hypothetical plant would be cut up into compartments or 

 cells, communicating throughout. Now it is just this view which 

 Sachs has lately brought forward so clearly and ably. A multi- 

 cellular plant does not grow and become complex because it 

 consists of numerous aggregated cells which increase and divide ; 

 but it becomes multicellular because it grows larger, and parti- 

 tion walls are placed in the mass partly for mechanical purposes, 

 partly to insure physiological distribution of labour. 



It is impossible, Sachs thinks, to hold the view that Vauckeria, 

 Caulerpa, and such plants have arisen by the degradation of 

 ancestors which formed cell-walls. It is also suggestive that the 

 nuclei in such "unicellular" plants are more closely packed at 

 the growing apex of the vesicle ; for we may thus understand how 

 the growing point of an organ with a single large apical cell only 

 differs in degree from one with numerous small apical cells. 



The consideration of all these matters leads to the conviction 

 that the cell-theory so long taught may have to be modified even 



more than it has been during the last ten or twelve years ; and 

 that once more we are being driven back to that centre of all 

 biological phenomena — the properties of protoplasm, multiple 

 and various in degree and in kind as they are. 



In conclusion, we cannot omit drawing attention to the im- 

 proved and refined methods employed by the careful and skilled 

 botanists of the younger school ; and it is to be hoped that those 

 who pass over the ground again will be at least equally well 

 equipped. It is not only reagents that are necessary in such 

 matters — critical power is indispensable as well as pure chemicals, 

 as any one may convince himself by the study of the recent 

 memoirs referred to, including the careful papers from Gardiner's 

 hands. One more point may well be insisted upon here : the 

 exhaustive study of a series of facts invariably brings them at 

 length into relation with other facts, and where neither series 

 is alone sufficient to base a scientific induction upon, converging 

 groups of observations may result in the establishment of very 

 important generalisations, leading to the recognition of still 

 larger consequences. There can be no question of the intrinsic 

 value of the observations on the continuity of protoplasm, apart 

 from the information they give in connection with physiological 

 matters ; but it is certain that they gain immensely in scientific 

 importance when looked at in the light afforded by recent dis- 

 coveries as to the behaviour of the nucleus and protoplasm in 

 cell division. 



NATIONAL WORK AND HEALTH 



""THE work of the International Juries was formally inaugu- 

 x rated at the Health Exhibition on Tuesday by H.R.H. the 

 Prince ot Wales. The principal address was given by Sir James 

 Paget, who chose as his subject "The Relation between 

 National Health and Work," especially as it may be shown in 

 a few of the many examples of the quantity of work which is 

 lost to the nation either through sickness or through deaths 

 occurring before the close of what may fairly be reckoned as the 

 working time of life. 



Sir James Paget went on to say : — I think it may be made 

 clear that this loss is so great that the consideration of it should 

 add largely to the motives by which all people may be urged to 

 the remedy of whatever unwholesome conditions they may live 

 in. It is a subject which is often in the minds of the real stu- 

 dents of the public health, but the public itself is far too little 

 occupied with it. 



In view of the national health and welfare, the pattern healthy 

 man is one who lives long and vigorously ; who in every part of 

 his life, wherever and whatever it may be, does the largest 

 amount of the best work that he can, and, when he dies, leaves 

 healthy offspring. And we may regard that as the healthiest 

 nation which produces, for the longest time and in proportion to 

 its population, the largest number of such men as this, and 

 which, in proportion to its natural and accumulated resources, 

 can show the largest amount and greatest variety of good work. 



Here let me insert, as an interpretation clause, that in all this 

 and what is to follow the word "man" means also "woman," 

 and "he " also means " she " ; and that when I speak of work 

 I mean not only manual or other muscular work, but work of 

 whatever kind that can be regarded as a healthy part of the 

 whole economy of the national life. And I shall take it for 

 granted that a large portion of all national welfare is dependent 

 on the work which the population can constantly be doing ; or, 

 if I may so express it, that the greater part of the national 

 wealth is the income from the work which is the outcome from 

 the national health. 



It is a common expression that we do not know the value of a 

 thing till we have lost it ; and this may be applied to the losses 

 of work which are due to the losses of national health. There 

 are very few cases in which these can be estimated with any 

 appearance of accuracy ; but I am helped to the best within our 

 present reach by Mr. Sutton, the Actuary to the Registry of 

 Friendly Societies. In^his office are the returns, for many years 

 past, of the sickness and mortality among the members of a very 

 large number of these Societies ; and, among other things, there 

 is recorded the number of days on which each member, when 

 "off work" on account of sickness, received money from his 

 Society. Hence Mr. Sutton can estimate, and this he has been 

 so good as to do for me, the average number of days' sickness 

 and consequent loss of work among several hundred thousands of 

 the workmen and others who are members of these Societies. 

 From the entire mass of these returns, he deduces that the 



