96 THE MICROSCOPICAL NEWS, 
sexual reproduction of Cryptogams, and his system was after- 
wards superseded by the natural system of De Jussieu and De 
Candolle. In 1782 Hedwig described the antheridia and pis- 
tillidia (archegonia) of Mosses. 
Although after this time the number of facts revealed by the micro- 
scope was wonderfully increased, yet little further real advance was 
made in scientific knowledge by means of the microscope until early 
in the present century, at which time the przuciples of nature were 
little understood. In the words of Sir John Lubbock, “Fifty years 
ago it was the general opinion that animals and plants came into 
existence just as we now see them. We took pleasure in their 
beauty ; their adaptation to their habits and mode of life in many 
cases could not be overlooked or misunderstood. Nevertheless, 
the book of nature was like some richly illuminated missal, 
written in an unknown tongue: the graceful forms of the letters, 
the beauty of the colouring, excited our wonder and admiration ; 
but of the true meaning little was known to us. Indeed, we 
scarcely realised that there was any meaning to decipher.” 
A new life, however, was soon infused into microscopical 
research upon the introduction of the achromatic object-glass 
about 1825 to 1830, and since that time enormous strides have 
been made in our knowledge of natural science, and especially of 
the phenomena of life and the laws of organisation. 
In 1838 Schleiden published his ‘‘Contributions to Phytogenesis,” 
in which he showed that the life-history of the cell must form the 
basis of vegetable physiology ; and in the following year Schwann 
issued from Berlin his “‘ Microscopical researches into the accord- 
ance in the structure and growth of animals and plants,” in which 
he showed the similitude in structure of the simpler forms of animals 
and plants, and how the various tissues arise, by differentiation of 
parts, from elementary cells. Cell-division was first described by 
Hugo von Mohl in 1835, who was also the first to detect, in 1846, 
the identity of the albuminous material (protoplasm) of vegetable and 
animal cells. About the same time Amici discovered the mode of 
fertilisation by means of the pollen-tube in flowering plants. In 1848 
Suminski completed the discovery of the reproductive process in 
Ferns. The mode of reproduction of other cryptogams was 
afterwards discovered, and embryology formed a part of scientific 
botany. 
In the animal kingdom the knowledge of embryonic life was much 
advanced by the discovery by Von Baer in 1827 of the ovarian ovum 
in mammals and man. He showed the similarity in the mode of 
origin of all vertebrate animals, that the development of the embryo 
is a progression from general to special structure, and laid the 
foundation of modern embryology, the recent progress of which is 
largely due to the methods that have been adopted of preparing 
