422 
NATURE 
| Marcu 4, 1897 
PHOTOGRAPHIC REPRODUCTION OF 
COLOURS. 
“THE various methods for producing photographic pictures in 
colour were described by Sir Henry Trueman Wood at the 
Society of Arts on February 24, and examples of the results 
achieved by the different processes were exhibited. The main 
object of the paper was to bring before the Society M. 
Chassagne’s promising process for the photographic repro- 
duction of colour, but the opportunity was taken to summarise 
the whole question of colour-photography. 
Though the va¢zonale of the new process remains a mystery, 
there can be no question that very remarkable results are pro- 
duced. Even more striking than M. Chassagne’s pictures, how- 
ever, are some transparencies exhibited at the same meeting by 
Mr. Bennetto, of Newquay, in Cornwall. For some time there 
have been rumours that Mr. Bennetto had obtained satisfactory 
photographs in colours, but the pictures had only been seen by 
a limited number of photographers before they were shown at 
the Society of Arts. His photographs are much clearer than those 
obtained by the Chassagne process, and look almost like water- 
colour sketches. 
A short account of a private exhibition of some of Mr. Ben- 
netto’s results appeared in Friday’s 7%es, and is here abridged. 
The methods, and indeed the principle, employed remain the 
secret of the inventor, and it is intended that they shall remain 
so until several more details and applications of the invention 
have been more fully worked out. All that is at present known 
is that the inventor claims to have discovered a system of colour 
photography by which can be transferred to a photographic 
negative, and thence printed on glass or paper, the exact natural 
colours of the object towards which the camera has been 
directed. He employs no pigments, his plates have not to be 
washed with various coloured solutions, and it is not necessary 
to view his pictures through any combination of tinted glasses. 
The colours are imprinted on the plate just as are the light and 
shade in an ordinary monochrome photograph, and are directly 
visible to the eye, without any subsidiary apparatus. It may be 
mentioned that Mr. Bennetto, in his earliest experiments, could 
get no effects with a less exposure than three minutes ; now he 
is able to work with exposures of sixteen seconds. 
In strictness, of course, it is not possible to know for certain 
that a particular result is produced by a particular process unless 
the nature of that process is also known ; and from that point of 
view, it is perhaps allowable to regard Mr. Bennetto’s pictures 
with some degree of philosophical suspicion. But he has been 
put to tests which it is difficult to suppose he could have satisfied 
did he not in fact do what he claims to do. He was requested 
to focts his apparatus on an easel. When he had done so, he 
was blindfolded, and on the easel was placed an impossible 
picture, painted in impossible colours, which he had never seen 
before. This he photographed and developed, still without see- 
ing the original, with the result that the impossible colours were 
reproduced in the photograph obtained. 
Whatever may have been the methods used, the pictures 
produced by them attain a high standard of excellence. One 
of the best specimens shown was a study of a sunrise, taken 
early one morning in the middle of June 1895, in which the 
fiery orange of the dawn and the heavy masses of cloud were 
admirably represented. The clouds, again, were excellent in 
a typical picture of Cornish seashore scenery, and the tints of 
the sand and rocks, and their reflections in the pools, were 
faithfully reproduced. In the case of a rock picture with 
wonderfully brilliant colouring, it was stated that, when the 
glass plate on which it was printed was examined under a 
microscope, not only could each individual mussel on the rocks 
in the foreground be clearly discerned, but that even the iri- 
descent colours en their shells were plainly distinguishable. 
Perhaps the picture which best illustrated the capabilities of 
the process was one of a champagne-bottle standing on a white 
tablecloth, and surrounded with various fruits. Here there 
were three or four different whites which were all distinguish- 
able, but which it would probably have taxed the powers of 
any artist to represent by painting. The gold-foil on the bottle 
was exactly rendered, and it was possible to tell that it was 
full by the gleam of the liquid. The inventor looks forward, 
among other things, to revolutionising by his process the illus- 
tration of books and magazines, and hopes to show in the 
future how to flash a picture on a screen so that a permanent 
copy may be left behind. 
NO. 1427, VOL. 55 
ON THE ALTERNATIONS OF GENERATIONS 
IN PLANT LIFE} 
[X his paper on apospory and allied phenomena (Zzz. 7rams. 
Bot., 2nd series, vol. il. p. 301) Prof. Bower says: ‘* Already 
the observations of Pringsheim and Stahl have had their 
effect in demonstrating that no fixed and impenetrable barrier 
exists between the sporophore and the oophore.” The 
suggestion thus made is far reaching in its consequences ; if 
there be no such fixed and impenetrable barrier, then the dis- 
tinction between the sporophore and oophore loses at least much 
of its value, and the anxious assignment of this or that structure 
to one or the other generation may prove to be labour lost ; then 
the doctrine of the alternation of generations is in peril, and the 
mind is driven to think of a state of things in which a man 
should find no impenetrable barrier between himself and his 
father or his grandmother. 
The doctrine of alternation of generations seems, therefore, to 
deserve reconsideration : and the principal object of the present 
paper is to endeavour to suggest to the attention of those more 
capable than myself of forming a conclusion, some considerations 
towards such a review of at least a part of the subject. 
Another question to which I desire to call attention as I 
proceed is this: whether reproduction is the function of special 
organs only, or whether it is more or less clearly shown to be a 
power possessed by the whole organism—a question to which 
the labours of Weismann have given a fresh interest. 
In this review I propose to confine my attention primarily to 
those classes of plants which produce a cormophyte. I do so, 
not forgetting that a wider survey of the subject might be yet 
more valuable. Under the term cormophyte I include the 
plant of the Characew, whether the description be perfectly 
accurate or not. 
I do not propose to trace the life-history of every group 
of plants; but I have chosen for consideration groups which 
exhibit, I believe, types of every important variety of the 
schemes of life-history to be found in those parts of the vegetable 
kingdom to which the doctrine in question has been thought to 
have any application. 
To prevent any possible misapprehension, let me say at once 
that when I use language borrowed from the doctrine in question, 
such as sporophore or oophytic generation, I do so, not as 
affirming the doctrine or the consequent fitness of the language, 
but in the endeavour to understand the view taken of the 
phenomena under discussion on the footing of that doctrine. 
Characee.—In this group we have a sexual generation. The 
fertilised archegone becomes a fruit or spermocarp; this is ° 
detached from the parent organism. It gives rise to a primary 
root and a hypha-like prothallus, and from the prothallus a young 
cormophyte is developed like the parent. The succession ot 
events may then be thus stated :— 3 
f Archegone | 
\ Antherizoid f 
| 
Spermocarp or fertilised archegone. 
Cormophyte producing 
Protonema or pro-embryo. 
Cormophyte. 
Now here we must observe that there is one kind of generating 
cell only, viz. the sexual cell, and that there is no spore in the 
sense of an asexual cell, and that, as a consequence, there is no 
sporophytic generation. 
On the first blush of the matter, a life-history such as this , 
would seem to present nothing like an alternation of generations. 
At one time, however, Prof. Vines suggested that the pro-embryo 
was to be regarded as the sporophore which did not produce 
spores, but aposporously produced the oophore by direct vege- 
table growth (see Bower, 2 Zz. Zr., p. 321). He has, how- 
ever, since altered his opinion, and he now regards the 
development of the pro-embryo not as indicative of an alter- 
nation of generations (Vines on Apospory in the Characez, 
1 Ann. Bot., 177). 
1 The accompanying paper reached the hands of the editor of NATURE on 
3x August of last year. Dr. Scott, in his valuable address as the President 
of the Botanical Section of the British Association, delivered more than a 
fortnight after that date, has, like myself, discussed the alternation of 
generations, apospory and apogamy, and the relations of mosses and ferns. 
These dates will account formy not referring to Dr. Scott’s views ; and on 
the whole I think it better to leave my paper as an independent contribution 
to these subjects, ratherahan to attempt to weave into its existing structure any 
references to the more authoritative contribution of Dr. Scott.—Epw. Fry. 
